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PubMed2005

Retinal nerve fiber layer measurements do not change after LASIK for high myopia as measured by scanning laser polarimetry with custom compensation.

PURPOSE: Scanning laser polarimetry (SLP) estimates retinal nerve fiber layer (RNFL) thickness through measurement of retardation of polarized light passing through the birefringent RNFL and cornea. A compensation method is incorporated to eliminate the anterior segment contribution to the total birefringence measured. LASIK is a technique that corrects myopia by ablating corneal tissue. This study evaluated RNFL measurements before and after LASIK as determined by SLP with a new custom compensation device set for the individual cornea before and after ablation. DESIGN: Interventional case series. PATIENTS AND METHODS: Patients underwent SLP measurements before and 30 days after LASIK for high myopia with customized compensation for anterior segment birefringence. Postoperative measurements were obtained with both the same compensation as was used preoperatively and with newly determined customized compensation. Standard RNFL parameters obtained before and after ablation with customized compensation were compared by use of paired Student's t tests with Bonferroni's correction for multiple comparisons. Postoperative measurements were also compared with those obtained preoperatively with the same corneal compensation measures as used preoperatively. MAIN OUTCOME MEASURES: Retinal nerve fiber layer parameters as determined by SLP before and after LASIK with 2 custom cornea compensator settings postoperatively. RESULTS: Fifty-seven eyes of 29 patients with myopia > -5.00 diopters underwent LASIK (average central ablation depth 101+/-11.3 mum). None of the 13 parameters showed statistically significant differences between preoperative and postoperative values with individually determined corneal compensation. When the preoperative corneal compensation was used postoperatively, 10 of 13 parameters were significantly changed. Comparison of the compensator settings before and after LASIK showed substantial differences in some individuals. On the average, there was a statistically significant change in the slow polarization axis of the cornea, with no statistically significant change in the magnitude of the birefringence, with some eyes showing increases and others decreases. The change in an individual cornea could not be predicted. CONCLUSIONS: Changes in RNFL measurements by SLP observed after LASIK in patients with high myopia are due to changes in corneal birefringence. These RNFL changes are not seen when customized compensation is applied for the cornea. Thus, LASIK does change the corneal birefringence but does not affect the RNFL.

Adult↗
PubMed2005

Full-thickness macular hole after LASIK for the correction of myopia.

PURPOSE: To describe 19 patients (20 eyes) who developed a macular hole (MH) after undergoing bilateral LASIK for the correction of myopia. DESIGN: Noncomparative, interventional, retrospective, multicenter case series. PARTICIPANTS: Nineteen patients (20 eyes) who developed an MH after bilateral LASIK for the correction of myopia at 10 institutions in Venezuela, Colombia, Puerto Rico, Spain, and the United States. METHODS: Chart review. MAIN OUTCOME MEASURE: Macular hole development. RESULTS: The MH formed between 1 to 83 months after LASIK (mean, 12.1). In 60% of cases, the MH developed < or =6 months after LASIK, and in 30% of cases it developed > or =1 year after LASIK. Eighteen of 19 (94.7%) patients were female. Mean age was 46 years (range, 25-65). All eyes were myopic (range, -0.50 to -19.75 diopters [mean, -8.9]). Posterior vitreous detachment was not present before and was documented after LASIK in 55% of eyes. A vitrectomy closed the MH on the 14 eyes that underwent surgical management, with an improvement of final best-corrected visual acuity in 13 of 14 (92.8%) patients. Our 20 eyes with a full-thickness MH after LASIK reflect an incidence of approximately 0.02% (20/83938). CONCLUSION: An MH may infrequently develop after LASIK for the correction of myopia. Our study shows that vitreoretinal surgery can be successful in restoring vision for most myopic eyes with an MH after LASIK. Vitreoretinal interface changes may play a role in MH formation after LASIK for the correction of myopia.

Adult↗
PubMed2006

Evidence for superior efficacy and safety of LASIK over photorefractive keratectomy for correction of myopia.

PURPOSE: To examine possible differences in efficacy and safety between LASIK and photorefractive keratectomy (PRK) for correction of myopia. DESIGN: Meta-analysis/systematic review. PARTICIPANTS: Patient data from previously reported prospective randomized controlled trials (PRCTs) and a systematic review of prospective case series in the Food and Drug Administration (FDA) clinical trials database. METHODS: A comprehensive literature search was performed using the Cochrane Collaboration methodology to identify PRCTs comparing LASIK and PRK for correction of myopia. A meta-analysis was performed on the results of PRCTs. In parallel, a systematic review of prospective data from FDA case series of LASIK and PRK for correction of myopia was undertaken. MAIN OUTCOME MEASURES: Key efficacy outcomes (uncorrected visual acuity [UCVA] > or = 20/20, +/-0.50 diopters [D] of the target mean refractive spherical equivalent) and safety outcomes (loss of > or =2 lines of best spectacle-corrected visual acuity [BSCVA], final BSCVA > or = 20/40, and final BSCVA < 20/25 where preoperative BSCVA was > or =20/20). RESULTS: Seven PRCTs were identified comparing PRK (683 eyes) and LASIK (403 eyes) for correction of myopia. More LASIK patients achieved UCVA > or = 20/20 at 6 months (odds ratio, random effects model [95% confidence interval], 1.72 [1.14-2.58]; P = 0.009) and 12 months (1.78 [1.15-2.75], P = 0.01). Loss of > or =2 lines of BSCVA at 6 months was less frequent with LASIK (2.69 [1.01-7.18], P = 0.05). Data from 14 LASIK (7810 eyes) and 10 PRK (4414 eyes) FDA laser approval case series showed that more LASIK patients achieved UCVA of 20/20 or better at 12 months (1.15 [1.03-1.29], P = 0.01), significantly more LASIK patients were within +/-0.50 D of target refraction at 6 months (1.38 [1.26-1.50], P<0.00001) and 12 months (1.21 [1.08-1.36], P = 0.0009) after treatment, and loss of > or =2 lines of BSCVA at 6 months was less frequent with LASIK (2.91 [2.22-3.83], P<0.00001). CONCLUSIONS: LASIK appears to have efficacy and safety superior to those of PRK. However, the data examined are from studies conducted > or =5 years ago. It is therefore unclear how our findings relate to present-day methods and outcomes. Further trials comparing contemporary equipment and techniques are needed to reevaluate the relative merits of these procedures.

Clinical Trials as Topic↗
PubMed2005

Evaluation of a clinical aberrometer for lower-order accuracy and repeatability, higher-order repeatability, and instrument myopia.

BACKGROUND: Refractive surgery has stimulated the development of aberrometers, which are instruments that measure higher-order aberrations. The purpose of this study was to test one clinical aberrometer, the Complete Ophthalmic Analysis System (COAS), for its accuracy, repeatability, and instrument myopia for measuring sphere and astigmatism and its repeatability for measuring higher-order aberrations. METHODS: Aberrations of 56 normal eyes (28 subjects) were measured with and without cycloplegia using a COAS, a conventional autorefractor and by subjective refraction. We evaluated lower-order accuracy (sphere and astigmatism) of the COAS and autorefractor by comparing that data with that of subjective refraction. We also tested COAS lower- and higher-order repeatability for 5 measurements taken in less than 1 minute. We evaluated instrument myopia by comparing cycloplegic and noncycloplegic measurements of the same eye. Data were analyzed for a 5.0-mm-diameter pupil. RESULTS: Mean COAS spherical error was between -0.1 and +0.4 diopters (D), depending on cycloplegia and the kind of sphere power computation selected. Cylinder power errors were less than 0.1 D. COAS repeatability coefficients were better than 0.25 D, and instrument myopia was less than 0.4 D. These were comparable with those of autorefraction. Higher-order repeatability was sufficient to allow reliable measurement of normal third-order aberrations and spherical aberration. CONCLUSIONS: Accuracy, repeatability, and instrument myopia of the COAS are similar to those of a conventional autorefractor. Accuracy and repeatability are also similar to those of subjective refraction. Like an autorefractor, the COAS provides instantaneous, objective measurements of sphere and astigmatism, but it also measures higher-order aberrations. We found that it is capable of reliably measuring problematic higher-order aberrations and is therefore a valuable asset for modern clinical eye care.

Adult↗
PubMed2005

Form-deprivation myopia in the guinea pig (Cavia porcellus).

Form deprivation (FD) was induced in 61 guinea pigs with a diffuser worn on one eye. The form-deprived eye elongated and developed myopia within 6 days in animals raised under a 12:12 h light/dark cycle, but not when reared in darkness. After 11 days of FD, the average eye was -6.6 D more myopic and 146 microm longer than its fellow eye. Initially the myopia was mostly from vitreous chamber elongation, but with longer periods of FD, corneal power increases predominated. These effects were confirmed in schematic eyes. After a delay, FD also elongated the vitreous chamber of the non-deprived eye. The myopia rapidly abated once the diffusers were removed (65% within 24 h) due to inhibition of elongation and choroidal thickening. The guinea pig provides a fast mammalian model of FD myopia and corneal curvature regulation.

Animals↗
PubMed2002

Pathologic myopia: where are we now?.

PURPOSE: To describe current concepts and available treatments for pathologic myopia. DESIGN: Review of experimental and clinical studies. METHODS: The demography, natural history, medical and surgical treatments for choroidal neovascular membrane, vitreoretinal interface disorders and future strategies for pathologic myopia are reviewed. RESULTS: Several medical and surgical modalities are currently available to treat various complications of pathologic myopia. Macular translocation appears to stabilize or improve visual function in many eyes with choroidal neovascularization. CONCLUSION: Newer strategies are emerging to better ameliorate or prevent the complications of pathologic myopia.

Animals↗
PubMed2003

Magnetic resonance imaging measurements of extraocular muscle path shift and posterior eyeball prolapse from the muscle cone in acquired esotropia with high myopia.

PURPOSE: To investigate extraocular muscle (EOM) path shift and prolapse of posterior eyeball from muscle cone in acquired esotropia with high myopia (AEHM), using magnetic resonance imaging. DESIGN: A case-control study. METHODS: There were 16 eyes with AEHM, 11 with high myopia (HM), 12 with moderate myopia (MM), and 11 control eyes. Extraocular muscle shift was evaluated by measuring angles formed by the line connecting orbital centroids and the line connecting each orbital centroid and each EOM centroid. The ratio of the prolapse in the posterior eyeball from the muscle cone was also measured. RESULTS: Both inferior shift of lateral rectus (LR) and nasal shift of superior rectus (SR) muscle were observed in the AEHM group, compared with HM, MM, and control groups. Neither shifted significantly in the HM group compared with control group. The prolapse ratio in AEHM group was higher than in the HM, MM, and control groups. Greater EOM shifts and eyeball prolapse were observed when the AEHM was more severe, as in esotropia fixus. CONCLUSIONS: In AEHM, a prolapsing eyeball shifts LR inferiorly and SR nasally; these findings were not observed in high myopia with neither ocular deviation nor restriction. These shifts reduce abduction and supraduction and increase infraduction and adduction in AEHM. The shifts would be predicted to create a hypoesodeviation, which is a common finding in AEHM. Both EOM shifts and superotemporal eyeball prolapse tend to be greater in esotropia fixus.

Case-Control Studies↗
PubMed1990

Myopia induced by vitreous hemorrhage.

Six of 11 children developed myopia in one eye after vitreous hemorrhage. None had retinopathy of prematurity, glaucoma, aphakia, or scleral buckling. In seven children developing vitreous hemorrhage before 1 year of age, six exhibited a myopic anisometropia in the affected eye of 1.37 to 12.00 diopters (mean, -4.7 diopters; S.D., 4.0). The degree of myopia correlated with the age of onset and duration of media opacification. In the child without myopia, the hemorrhage did not obscure the posterior pole. None of the four children whose hemorrhage occurred after 2 1/2 years of age showed myopic anisometropia (mean, +0.16 diopters; S.D., 0.24). We conclude that vitreous hemorrhage occurring in infancy is strongly associated with the development of myopia in the affected eye.

Aging↗
PubMed1999

Corneal sensitivity after photorefractive keratectomy and laser in situ keratomileusis for low myopia.

PURPOSE: To evaluate and compare the recovery of postoperative corneal sensitivity after laser in situ keratomileusis and photorefractive keratectomy for the correction of low myopia. METHODS: In a prospective study, 17 consecutive eyes (17 patients) underwent laser in situ keratomileusis to correct myopia ranging from -3.25 to -6.75 diopters, and another 18 consecutive eyes (18 patients) underwent photorefractive keratectomy to correct myopia from -3.12 to -7.00 diopters. Corneal sensitivity was tested preoperatively and 1 week and 1, 3, and 6 months postoperatively using the Cochet-Bonnet esthesiometer. Corneal sensitivity was tested at the center of the cornea, and in four additional central points 2 mm from the corneal center (nasal, inferior, temporal, and superior). RESULTS: Corneal sensitivity after laser in situ keratomileusis was reduced at the ablated zone during the first 3 months after surgery (Wilcoxon rank sum test, P < .05), and only after 6 months it returned to its preoperative values. However, corneal sensitivity recovered its preoperative values 1 month after photorefractive keratectomy (Wilcoxon rank sum test, P > .05), except for the central corneal point, where 3 months were required. Comparing both groups, corneal sensitivity was more depressed after laser in situ keratomileusis than after photorefractive keratectomy during the first 3 months (Mann-Whitney test, P < .05), except for the nasal central point, although no differences were found between both groups at 6 months (P > .05). CONCLUSIONS: In the correction of low myopia, corneal sensitivity at the ablated zone was more depressed after laser in situ keratomileusis than after photorefractive keratectomy during the first 3 months after surgery. Only after 6 months were corneal sensitivity values similar in both groups.

Adult↗
PubMedDate not supplied

Laser subepithelial keratomileusis for low to moderate myopia: 6-month follow-up.

PURPOSE: To examine the effectiveness, safety, and stability of laser subepithelial keratomileusis (LASEK), a modified photorefractive keratectomy for low to moderate myopia. METHODS: This study evaluated the results of LASEK in 48 myopic patients (84 eyes) with a consecutive 6-month follow-up period. Preoperative myopia ranged from 3.25 to 7.00 diopters (D). Uncorrected and corrected visual acuity, manifest refraction, epithelial healing time, postoperative pain, subepithelial corneal haze, and complications were examined. RESULTS: Uncorrected visual acuity of 20/30 or better was achieved in 78.6% of eyes at 1 week and in 96.4% at 6 months after surgery. A mean refraction of within +/-0.50 D was measured in 42 eyes (50.0%) and +/-1.0 D in 79 eyes (94.0%) at 6 months. The epithelial healing time was 3.68 +/- 0.69 days (range, 3-6 days) and postoperative pain scores were 1.49 +/- 0.65. The subepithelial corneal haze scores were 0.56 +/- 0.34 and 0.16 +/- 0.25 at 1 and 6 months, respectively. As for complications, alcohol leakage during surgery occurred in 3 eyes, incomplete epithelial detachment in 3 eyes, contact lens intolerance in 5 eyes and steroid-induced elevated intraocular pressure (>21 mm Hg) in 1 eye. CONCLUSIONS: LASEK is an effective and safe procedure for low to moderate myopia. It can be considered an alternate type of refractive surgery for correction of low to moderate myopia.

Adult↗
PubMed2002

Blur detection thresholds in childhood myopia: single and dual target presentation.

There is some suggestion that the ability to detect blur may be altered in adults with myopia. Here, we address the question of whether children with myopia have worse blur detection than other children, and whether blur detection in myopic children is related to the rate of myopia progression. We recruited 20 myopes and 20 non-myopes aged between 8 and 12 years. Refractive errors, visual acuity, and contrast sensitivity were measured and the change in refractive error over the past year calculated from clinic records. Blur detection thresholds for two different types of black and white targets (text and scenes), two illumination conditions and two testing protocols were determined using a computer-based forced-choice testing procedure. The two testing protocols used were: (i) dual image presentation where subjects were asked to choose the clearer of the two images, one image always having zero blur, and (ii) single image presentation in which the subject reported whether the image was clear or blurred. Blur discrimination ability under all tested conditions was similar for both refractive error groups. Blur detection thresholds were 0.27+/-0.15 D (myopes) and 0.24+/-0.07 D (non-myopes) for text images. Thresholds were similar when measured with a one log unit reduction in lighting: 0.27+/-0.31 D compared to 0.23+/-0.14 D. Blur detection thresholds were greater for photographic scenes (myopes 0.41+/-0.36 D, non-myopes 0.44+/-0.36 D) and when only a single text image (myopes 0.51+/-0.21 D, non-myopes 0.59+/-0.01 D) was presented, but this increase was measured in both refractive error groups. There was no correlation between blur thresholds and refractive error magnitude, refractive error progression over the past year, or contrast sensitivity. We found that the blur detection ability showed greater individual variation in myopic children. Further work is required to determine whether blur detection ability is of relevance to myopia development.

Accommodation, Ocular↗
PubMed1999

Long-term changes in retinal contrast sensitivity in chicks from frosted occluders and drugs: relations to myopia?

Experiments in animal models have shown that the retinal analyzes the image to identify the position of the plane of focus and fine-tunes the growth of the underlying sclera. It is fundamental to the understanding of the development of refractive errors to know which image features are processed. Since the position of the image plane fluctuates continuously with accommodative status and viewing distance, a meaningful control of refractive development can only occur by an averaging procedure with a long time constant. As a candidate for a retinal signal for enhanced eye growth and myopia we propose the level of contrast adaptation which varies with the average amount of defocus. Using a behavioural paradigm, we have found in chickens (1) that contrast adaptation (CA, here referred to as an increase in contrast sensitivity) occurs at low spatial frequencies (0.2 cyc/deg) already after 1.5 h of wearing frosted goggles which cause deprivation myopia, (2) that CA also occurs with negative lenses (-7.4D) and positive lenses (+6.9D) after 1.5 h, at least if accommodation is paralyzed and, (3) that CA occurs at a retinal level or has, at least, a retinal component. Furthermore, we have studied the effects of atropine and reserpine, which both suppress myopia development, on CA. Quisqualate, which causes retinal degeneration but leaves emmetropization functional, was also tested. We found that both atropine and reserpine increase contrast sensitivity to a level where no further CA could be induced by frosted goggles. Quisqualate increased only the variability of refractive development and of contrast sensitivity. Taken together, CA occurring during extended periods of defocus is a possible candidate for a retinal error signal for myopia development. However, the situation is complicated by the fact that there must be a second image processing mode generating a powerful inhibitory growth signal if the image is in front of the retina, even with poor images (Diether, S., & Schaeffel, F. (1999).

Adaptation, Ocular↗
PubMed2000

Videokeratography after excimer laser in situ keratomileusis for myopia.

OBJECTIVE: The purpose of this study was to define qualitative patterns of videokeratography after excimer laser in situ keratomileusis (LASIK) for myopia and to identify associations of videokeratography patterns with clinical variables. DESIGN: Single-center, retrospective, cohort study. PARTICIPANTS: One hundred twenty-six eyes of 68 patients with myopia who desired surgical correction of myopia ranging from -1.50 to -8.80 diopters. INTERVENTION: Myopia was corrected with LASIK using a Summit OmniMed/Apex excimer laser. Computer-assisted videokeratography data were acquired at 3 months after primary LASIK, and associations of videokeratography pattern with clinical variable were assessed. MAIN OUTCOME MEASURES: Seven subgroup ablation zone patterns were characterized using tangential curvature maps; these subgroups were combined into pooled symmetric and asymmetric groups. Associations with age, attempted correction, single-zone or multizone ablation, postoperative uncorrected and spectacle-corrected visual acuity, predictability, astigmatism, corneal uniformity, glare disability, and contrast sensitivity were analyzed. RESULTS: Thirty-two eyes (25.4%) showed a uniform pattern, 14 eyes (11.1%) showed a bow-tie pattern, 22 eyes (17.5%) showed a peninsula pattern, 22 eyes (17.5%) showed a semicircular pattern, 22 eyes (17.5%) showed an off-center blue spot pattern, 10 eyes (7.9%) showed an irregular pattern, and 4 eyes (3.2%) showed a central island pattern. Spectacle-corrected visual acuity, astigmatism, corneal uniformity, glare disability, and contrast sensitivity were significantly related to videokeratography pattern, although the difference among videokeratography groups was clinically small. Age, attempted correction, single- or multizone ablation, and postoperative uncorrected visual acuity and predictability were not predictive of videokeratography pattern. CONCLUSIONS: Most eyes in this study had an asymmetric videokeratography pattern 3 months after LASIK. Small but statistically significant differences were identified among the videokeratography patterns that potentially may affect postoperative quality of vision.

Adolescent↗
PubMed2000

Ultrasonographic measurement of induced myopia associated with capsular bag distention syndrome.

OBJECTIVE: To determine the causes of postoperative myopia associated with capsular bag distention syndrome (CBDS) and characterize the associated findings. DESIGN: Prospective, multicenter, nonrandomized, comparative (self-controlled) trial. PARTICIPANTS: Six eyes from six patients had CBDS develop after phacoemulsification and posterior chamber intraocular lens implantation. METHODS: Keratometric values, axial length, visual acuity, and manifest refraction were assessed in each eye. Using 20-MHz (I3SYSTEM-ABD, Innovative Imaging Inc, Sacramento, CA) and 50-MHz (Ultrasound Biomicroscope, Zeiss Humphrey Systems, Dublin, CA) ultrasonographic probes, images and measurements of the anterior segment were obtained. After neodymium:yttrium-aluminum-garnet (Nd:YAG) capsulotomy, these measures were repeated and correlated with predicted and actual refractive changes. MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), manifest refraction, and anterior chamber depth before and after treatment of CBDS. RESULTS: Although intended postoperative refraction averaged -0.58 diopters (D) (range, -0.12 to -1.63 D), eyes with CBDS had an average spherical equivalent refraction of -2.35 D (range, +0.13 to -4.50 D), P < 0.05 (one-tailed, paired t test). BCVA averaged 20/24 (range, 20/15-20/40-1), but UCVA averaged 20/133 (range, 20/60 to 20/400). Average distance from the corneal surface to the anterior intraocular lens (IOL) optic surface was 3.55 mm in eyes with CBDS, and 4.30 mm after Nd:YAG capsulotomy. Posterior movement of the IOL optic after capsulotomy accounted for 1.23 D of hyperopic shift or 82% of the CBDS-induced myopia. Treatment of CBDS resulted in both improved UCVA and BCVA. Nd:YAG capsulotomy also released the colloidal suspension within the capsular bag posterior to the IOL optic. The incidence of CBDS was 0.3% in one of the practices reviewed. CONCLUSIONS: Capsular bag distention syndrome includes unexpected myopia and poor UCVA after cataract surgery with lens implantation in cases involving a continuous capsulorhexis. A dramatic posterior distention of the posterior capsule is observed, as well as anterior chamber shallowing, tight apposition of the iris to the IOL, and anterior bowing of the iris. A slightly turbid colloidal suspension behind the IOL implant and late posterior capsular fibrosis are also observed. Timely treatment of CBDS can correct unwanted myopia, improve UCVA and BCVA, and restore normal anatomic relationships in the eye.

Aged↗
PubMed2001

Laser in situ keratomileusis for myopia up to -11 diopters with up to -5 diopters of astigmatism with the summit autonomous LADARVision excimer laser system.

OBJECTIVE: To assess the safety and effectiveness of the Summit Autonomous LADARVision active tracking narrow beam excimer laser system for laser in situ keratomileusis (LASIK) correction of myopia and astigmatism. DESIGN: A multicenter, prospective noncomparative case series. PARTICIPANTS: This cohort consisted of 177 eyes corrected for spherical myopia up to -11 diopters (D) and 170 eyes corrected for myopia up to -11 D spherical equivalent with astigmatism up to -5 D. INTERVENTION: Treatments were performed at four sites in the United States using a 6-mm optic zone for spherical myopes and a 5.5-mm optic zone with a 1-mm blend for astigmats. MAIN OUTCOME MEASURES: Visual acuity, subjective refraction, vector analysis, subject satisfaction, intraocular pressure, complications, and adverse reactions. RESULTS: Six-month follow-up was available on 157 spherical eyes and 113 astigmatic eyes. For spherical myopes, uncorrected visual acuity (UCVA) was 20/20 or better in 60.5%, 20/25 or better in 80.3%, and 20/40 or better in 93.9%. The mean spherical equivalent was -0.29 +/- 0.45 D with 75.2% +/- 0.50 D and 94.9% +/- 1.00 D of intended. A loss of two lines of best spectacle-corrected visual acuity (BSCVA) occurred in 0.6%, and no eyes lost greater than two lines of BSCVA. For astigmatic myopes, UCVA was 20/20 or better in 52.0%, 20/25 or better in 74.5%, and 20/40 or better in 94.1%. The mean spherical equivalent was -0.23 +/- 0.49 D with 75.2% +/- 0.50 D and 95.6% +/- 1.00 D of intended. A loss of two lines of BSCVA occurred in 0.9%, and no eyes lost greater than two lines of BSCVA. Vector analysis showed that 99% of the intended cylinder was corrected on average with a mean angle of error of 4.2 degrees. Refractive stability was achieved between 1 and 3 months in 97.5% of spherical eyes and 99.4% of astigmatic eyes and confirmed between 3 and 6 months in 100% of both spherical and astigmatic eyes. CONCLUSIONS: Eyes treated for myopia up to -11 D of spherical equivalent with or without astigmatism up to -5 D show early refractive stability, good UCVA outcomes, no significant loss of BSCVA, accurate correction of astigmatism, and slight undercorrection without a change from the photorefractive keratectomy algorithm and with a single treatment.

Adult↗
PubMed2001

Two-year outcomes of intrastromal corneal ring segments for the correction of myopia.

OBJECTIVE: To evaluate the safety and efficacy of Intrastromal Corneal Ring Segments (ICRS) for the correction of myopia. DESIGN: Nonrandomized, comparative trial. PARTICIPANTS: Patients enrolled in the United States Food and Drug Administration phase II and phase III clinical trials of the ICRS had best spectacle-corrected visual acuity (BSCVA) of 20/20 or better, myopia of -1.00 to -3.50 diopters (D), and a cylindrical correction of 1.00 D or less as measured by manifest refraction. INTERVENTION: Surgical correction of myopia with an ICRS. MAIN OUTCOME MEASURES: Efficacy was assessed by predictability of refractive outcome (deviation from predicted cycloplegic refraction spherical equivalent), stability of refractive effect, and postoperative uncorrected visual acuity. Safety was assessed by adverse events, maintenance or loss of preoperative BSCVA, and induced manifest refraction cylinder. RESULTS: Four hundred fifty-two patients were enrolled at 11 investigational sites in both studies. Of the 454 surgical attempts, 449 received an ICRS in one eye (0.25, 0.30, and 0.35 mm in 148, 151, and 150 eyes, respectively). First surgeries were attempted in 452 patients. An ICRS was successfully implanted in 447 initial eyes, and 5 surgeries were discontinued. Of the five discontinued surgeries, three patients subsequently exited from the study, and two patients went on to have the ICRS implanted in the second eye, bringing the total number of successful implants to 449 patient eyes. Month 24 postoperative follow-up was completed on 358 patients (80%). At month 24, 328 of 354 eyes (93%) were within +/-1.00 D of predicted refractive outcome. Refraction changed by 1 D or less in 97% of eyes (421/435) between 3 and 6 months after implantation and in 99% (343/348) between months 18 and 24. Before surgery, 87% of eyes (390/448) saw worse than 20/40 uncorrected; 24 months after surgery, 55% of eyes (196/358) saw 20/16 or better, 76% (271/358) saw 20/20 or better, and 97% (346/358) saw 20/40 or better. Although two eyes (2/358; 0.5%) lost two or more lines of BSCVA at 24 months; visual acuity in both was 20/20 or better. Intraoperative complications included anterior corneal surface perforation (three eyes) and anterior chamber perforations (two eyes, one during an attempted exchange procedure); all healed spontaneously without suturing and without loss of BSCVA. The ICRS was repositioned in five eyes to increase correction. Postoperative complications in one eye each were infectious keratitis, shallow segment placement, and loss of two lines of BSCVA at two or more consecutive examinations (subsequently regained). CONCLUSIONS: The ICRS safely, predictably, and effectively reduced or eliminated myopia of -1.00 to -3.50 D. The refractive effect was stable over time.

Adult↗
PubMed2003

Verteporfin therapy of subfoveal choroidal neovascularization in pathologic myopia: 2-year results of a randomized clinical trial--VIP report no. 3.

PURPOSE: To report 24-month vision and fluorescein angiographic outcomes from trials evaluating photodynamic therapy with verteporfin in patients with subfoveal choroidal neovascularization (CNV) caused by pathologic myopia. DESIGN AND SETTING: Multicenter, double-masked, placebo-controlled, randomized clinical trial at 28 ophthalmology practices in Europe and North America. PARTICIPANTS: Patients with subfoveal choroidal neovascular lesions caused by pathologic myopia measuring no more than 5400 micro m and best-corrected visual acuity (approximate Snellen equivalent) of 20/100 or better. METHODS: Similar to methods described for 1-year results with follow-up examinations beyond 1 year, continuing every 3 months (except Photograph Reading Center evaluations only at the month 24 examination). During the second year, the same regimen (with verteporfin or placebo as applied at baseline) was used if angiography showed fluorescein leakage from CNV. MAIN OUTCOME MEASURES: The primary outcome was the proportion of eyes with fewer than 8 letters (approximately 1.5 lines) of visual acuity loss at the month 24 examination, adhering to an intent-to-treat analysis and using the last observation carried forward method to impute for any missing data. RESULTS: Seventy-seven of 81 patients (95%) in the verteporfin group, compared with 36 of 39 patients (92%) in the placebo group, completed the month 24 examination. At this time point, 29 of 81 verteporfin-treated patients (36%) compared with 20 of 39 placebo-treated patients (51%) lost at least 8 letters (P = 0.11). The distribution of change in visual acuity at the month 24 examination was in favor of a benefit for the cases assigned to verteporfin (P = 0.05). This included improvement by at least 5 letters (equivalent to at least 1 line) in 32 verteporfin-treated cases [40%] vs. five placebo-treated cases (13%) and improvement by at least 15 letters (equivalent to at least 3 lines) in 10 verteporfin-treated cases (12%) vs. zero placebo-treated cases. No additional photosensitivity adverse reactions or injection site adverse events were associated with verteporfin therapy in the second year of follow-up. CONCLUSIONS: Verteporfin therapy for subfoveal CNV caused by pathologic myopia safely maintained a visual benefit compared with a placebo therapy through 2 years of follow-up. Although the primary outcome was not statistically significantly in favor of verteporfin therapy at 2 years as it had been at 1 year of follow-up, the distribution of change in visual acuity at the month 24 examination was in favor of the verteporfin-treated group and showed that this group was more likely to have improved visual acuity through the month 24 examination. The VIP Study Group recommends verteporfin therapy for subfoveal CNV resulting from pathologic myopia based on both the 1- and 2-year results of this randomized clinical trial.

Adult↗
PubMed1979

Prescribing glasses for myopia.

Myopia is a one-symptom refraction problem: blurring of distance vision. Correction of the myopia should eliminate this symptom, but a prescription for glasses may, in fact, produce other symptoms equally--or more--disturbing. A few of the more common pitfalls in prescribing for the myopic patient are: (1) failure to recognize accommodative stress masquerading as low myopia; (2) confusion as to when, or whether, to prescribe for the unilateral myopic patient; (3) overcorrecting the myopic refractive error and failure to appreciate the symptoms that result from overcorrection; (4) difficulties in gaining acceptance of bifocals by the myopic presbyopic patient; (5) appropriate selection of bifocal segments; and (6) acquired myopic anisometropia caused by sclerosis of the crystalline lens. Although myopia would appear to be the least troublesome of all refractive problems, the maximizing of visual potential with comfort and safety needs refracting skills, experience, and clinical judgement.

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