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PubMed2006

Analysis of patients with good uncorrected distance and near vision after monofocal intraocular lens implantation.

PURPOSE: To analyze factors contributing to uncorrected visual acuity of at least 6/12 for distance and at least J4 for near (pseudoaccommodation) after monofocal intraocular lens (IOL) implantation. SETTING: Iladevi Cataract and IOL Research Center, Ahmedabad, India. METHODS: In a case-controlled study of 30 eyes (30 patients) that had phacoemulsification, those with pseudoaccommodation were assigned to cases and 30 eyes (30 patients) without pseudoaccommodation were designated as controls. Controls were matched by identical best corrected visual acuity, age, and postoperative duration. Subjective refraction was done with retinoscopy. Factors analyzed included corneal astigmatism, pupil size, axial IOL movement, amplitude of accommodation, axial length (AL), and age. Corneal astigmatism was noted on topography and interpreted as against the rule (ATR) (180 +/- 15 degrees), with the rule (WTR) (90 +/- 15 degrees), and oblique (OB) (45/135 +/- 30 degrees). Pupil size was noted on topographic display and AL and anterior chamber depth (ACD) on immersion A-scan. The axial IOL movement was calculated as the difference in ACD after instillation of cyclopentolate 1% (Cyclopent) and subsequently pilocarpine nitrate 2% (Carpinol) at separate visits, and amplitude of accommodation was measured with static and dynamic retinoscopy. Multivariate logistic regression and odds ratio with 95% confidence intervals were determined. RESULTS: Mean spherical equivalent was -0.45 +/- 0.63 diopter (D) in cases and -0.35 +/- 0.83 D (P = .61) in controls. Multivariate logistic regression in cases versus controls: corneal astigmatism (ATR versus WTR and OB collectively): 10.19 [1.8,57.44], P = .009; pupil size: 0.45 [0.07,2.71], P = .38; axial IOL movement: 1.39 [0.51,0.77], P = .514; amplitude of accommodation: 2.95 [0.93,9.3], P = .065; AL: 0.55 [0.29,1.02], P = .058; and age: 0.98 [0.5,1.95], P = .963. CONCLUSION: The study suggests a significant role of ATR corneal astigmatism in good uncorrected distance and near vision after monofocal IOL implantation.

Accommodation, Ocular↗
PubMed2006

Hyperopic shift in refraction associated with implantation of the single-piece Collamer intraocular lens.

PURPOSE: To describe reports of refractive hyperopic shift over time following intraocular lens (IOL) implantation, discuss possible etiologies, and suggest preventive and therapeutic treatments. SETTING: Multiple U.S. ophthalmic surgical centers; data collection at Staar Surgical, Monrovia, California, USA. METHODS: Forty cases displaying a progressive hyperopic shift in refraction after implantation of the single-piece Collamer IOL (Staar Surgical) were reported to the manufacturer out of 160 000 that have been implanted since its commercial introduction in April 2000. A retrospective data analysis of these 40 cases was performed; parameters included the mean refractive change over time, presence of capsular fibrosis, IOL displacement, and outcomes of secondary treatments. Individual case examples are presented. RESULTS: The mean refractive shift was 1.81 diopters (D) (range 0.25 to 3.75 D) with 5 cases (14%) demonstrating a hyperopic shift greater than 3.0 D. In 38 of the 40 cases, some combination of the following were reported: posterior displacement of the IOL, capsule fibrosis, and/or relief of the condition by performance of a radial or circumferential anterior neodymium:YAG capsulotomy to relieve capsule tension. The use of a small (less than 5.5 mm) capsulorhexis was also associated with cases showing the hyperopic shift. CONCLUSION: The most likely etiology was the development of anterior capsule fibrosis, sometimes exacerbated by a small capsulorhexis, which could cause the IOL to move posteriorly, resulting in a hyperopic change in refraction. Previous in vitro testing by the manufacturer ruled out a change in the refractive power of the IOL in the eye as a cause of this phenomenon.

Aged↗
PubMed2006

Anterior segment OCT and phakic intraocular lenses: a perspective.

Perfect tolerance is expected when one implants a phakic intraocular lens (pIOL) in the anterior segment. Not only should the material be compatible, but the pIOL must respect the anatomy of the anterior chamber. Based on 3 years of experience using an anterior segment optical coherence tomographer (Visante OCT, Carl Zeiss Meditec), I have defined numerous safety criteria for pIOLs. The internal dimensions of the anterior chamber must be considered along different meridians. I propose an objective measurement of the iris dome, the crystalline lens rise (CLR), which is the distance between the anterior pole of the crystalline lens and a line joining the 2 opposite iridocorneal angles. In a series with the Artisan IOL (Ophtec), pigment dispersion syndrome appeared in 70% of cases in which the CLR was greater than 600 microm. Angle-supported IOLs must be placed relative to the anterior chamber's largest diameter; in the same series of cases, the anterior chamber was oval with a large vertical axis in 74% of cases. The posterior face of an angle-supported IOL must have a 700 microm vault to respect the physiological modifications of the crystalline lens. It is difficult to know the posterior chamber's exact diameter as it varies with the horizontal or vertical axis. It also undergoes constant modifications due to accommodation and aging.

Adult↗
PubMed2006

Estimation of true corneal power after keratorefractive surgery in eyes requiring cataract surgery: BESSt formula.

PURPOSE: To describe a new formula, BESSt, to estimate true corneal power after keratorefractive surgery in eyes requiring cataract surgery. SETTING: Moorfields Eye Hospital, London, United Kingdom. METHODS: The BESSt formula, based on the Gaussian optics formula, was developed using data from 143 eyes that had keratorefractive surgery. The formula takes into account anterior and posterior corneal radii and pachymetry (Pentacam, Oculus) and does not require pre-keratorefractive surgery information. A software program was developed (BESSt Corneal Power Calculator), and corneal power was calculated in 13 eyes that had keratorefractive surgery and required cataract surgery. RESULTS: In the eyes having phacoemulsification, target refractions calculated with the BESSt formula were statistically significantly closer to the postoperative manifest refraction (mean deviation 0.08 diopters [D] +/- 0.62 [SD]) than those calculated with other methods as follows: history technique (-0.07 +/- 1.92 D; P = .05); history technique with double-K adjustment (0.13 +/- 2.39 D; P = .05); Holladay 2 with K-values estimated with the contact lens method (-0.76 +/- 1.36 D; P = .03); Holladay 2 with K-values from Atlas topographer (Humphrey) (-0.55 +/- 0.61 D; P<.01). Using the BESSt formula, 46% of eyes were within +/-0.50 D of the intended refraction and 100% were within +/-1.00 D. CONCLUSIONS: The BESSt formula was statistically significantly more accurate than the other techniques tested. Thus, it could significantly improve intraocular lens power calculation accuracy after keratorefractive surgery, especially when pre-refractive surgery data are unavailable.

Astigmatism↗
PubMed2003

Responsiveness of the National Eye Institute Refractive Error Quality of Life instrument to surgical correction of refractive error.

OBJECTIVE: Refractive error and the means by which it is corrected may impact substantially on quality of vision and health-related quality of life in ways not captured adequately by standard measures of visual acuity. The goal of this analysis was to evaluate the responsiveness of the National Eye Institute Refractive Error Quality of Life (NEI-RQL) instrument to surgical correction of refractive error. DESIGN: Prospective, multicenter cohort study. PARTICIPANTS: The NEI-RQL, a 42-item measure with 13 scales, was self-administered by 185 patients before and after undergoing surgical correction of myopic or hyperopic refractive error. Preoperative and postoperative clinical information was collected, including refractive error and corrected visual acuity. METHODS: Differences between preoperative and postoperative NEI-RQL scores were examined. Responsiveness was assessed using the standardized response mean and the responsiveness statistic. We also compared scales using relative efficiency estimates. MAIN OUTCOME MEASURES: Changes in NEI-RQL scales (clarity of vision, expectations, near vision, far vision, diurnal fluctuations, activity limitations, glare, symptoms, dependence on correction, worry, suboptimal correction, appearance, and satisfaction with correction). RESULTS: For myopes and hyperopes combined, refractive surgical correction was associated with statistically significant (P<0.05) improvements in scores for 11 of 13 scales. The largest improvements, ranging from 26 to 58 points on the 0 to 100 possible score range, were seen in expectations, activity limitations, dependence on correction, appearance, and satisfaction with correction. Separate analysis of myopes and hyperopes revealed similar effects in the 2 groups. Baseline scores were found to be predictive of change after surgery. CONCLUSIONS: The NEI-RQL is responsive to changes in vision-targeted health-related quality of life resulting from keratorefractive surgery. This instrument may prove useful for evaluating the beneficial and adverse impacts of surgical and nonsurgical methods of refractive error correction.

Adult↗
PubMed2004

The axial length/disc area ratio in anisometropic hyperopic amblyopia: a hypothesis for decreased unilateral vision associated with hyperopic anisometropia.

OBJECTIVE: Hyperopic anisometropia is a risk factor for amblyopia. Disc areas and axial lengths are reduced in amblyopic eyes. This study's aim was to investigate the differences in the relative size of the optic disc in 5 groups of eyes: (1) normal right eyes; (2) smaller eyes of nonamblyopic, anisometropic, bilateral hyperopes; (3) larger eyes of nonamblyopic, anisometropic, bilateral hyperopes; (4) fellow (nonamblyopic) eyes of eyes of amblyopic, anisometropic, bilateral hyperopes; and (5) amblyopic eyes of bilateral hyperopic anisometropes. To determine the relative size of the discs, the relationships of axial length to disc area in the above groups were evaluated. DESIGN: Case-control study. PARTICIPANTS: Nine hundred twenty-seven records from the author's private practice, which included axial length measurements and optic disc photographs or digital images, were analyzed to form the 5 groups above. METHODS: Disc areas were measured using objective techniques developed by Bengtsson and Krakau. Axial lengths were determined by ultrasound biometry or with a Zeiss IOL Master. MAIN OUTCOME MEASURES: Optic disc areas, corrected for magnification, axial lengths, and a derived ratio, axial length/disc area (AXL/DA). RESULTS: The AXL/DA for the amblyopic eyes (group 5) was significantly greater than that of all of the other groups, indicating that amblyopic eyes have discs that are both absolutely smaller and, when adjusted for eyes' size, relatively smaller than those of nonamblyopic eyes. CONCLUSION: The relatively small size of the discs of amblyopic eyes points to an organic as opposed to a functional amblyopia in these patients.

Adolescent↗
PubMed2005

Five-year refractive changes in an adult population: Reykjavik Eye Study.

PURPOSE: To study refractive changes over the course of 5 years in citizens of Reykjavik 50 years and older at baseline. METHODS: The cohort was a population-based random sample of citizens 50 years and older. Eight hundred forty-six of the 958 survivors (88.2%) underwent a 5-year follow-up examination. Refraction and keratometry were performed using a Nidek (Gamagori, Japan) ARK 900 autorefractor keratometer. Typing and grading of lens opacification was carried out using Scheimpflug slit-lamp and retroilluminated images (Nidek EAS 1000), and axial length was measured by Nidek Echoscan 800. RESULTS: Seven hundred fifty-seven right eyes were available for refraction analysis. In the 50- to 59-year age group and the 60- to 69-year age group at baseline, there was a hyperopic shift of 0.41 diopters (D) and 0.34 D, respectively, during the 5 years. There was a 0.02-D myopic shift for those 70 years of age and older at baseline during the same period. Considering all right eyes, there was a hyperopic shift of +0.29 D over the 5 years, whereas eyes with nuclear lens opacification grade II or more at baseline had a mean myopic shift of -0.65 D. There was a mean change of 0.13 D in the astigmatism against the rule during the 5 years. The data on axial length are available from the follow-up study only. The mean axial length for those 50 to 59 years of age at baseline was 23.56 mm (standard deviation [SD], 1.08 mm), as compared with 23.23 mm (SD, 1.27 mm) for those 70 years of age and older at baseline (P<0.04). CONCLUSIONS: We found a hyperopic shift for those younger than 70 years of age at baseline, although eyes with nuclear opacification grade of II or more at baseline were associated with a myopic shift. There was also an age-related shift against the rule for the axis of astigmatism during the 5-year period. Our results may be useful for predicting long-term outcome of refractive surgery.

Age Distribution↗
PubMed2005

Pre-excimer laser and post-excimer laser refractive surgery measurements of scotopic pupil diameter using 2 pupillometers.

PURPOSE: To compare a digital infrared pupillometer with a handheld light amplification pupillometer for measuring scotopic pupil size and to evaluate if the postoperative refractive changes of the cornea can influence pupil measurements. DESIGN: Prospective noncomparative interventional case series. PARTICIPANTS: One hundred eyes, 50 myopic (mean spherical equivalent [SE] refraction [+/- standard deviation], -4.32+/-2.44 diopters [D]) and 50 hyperopic (mean SE refraction, +2.95+/-0.99 D), of 50 otherwise healthy subjects underwent photorefractive keratectomy or LASIK. INTERVENTION: The preoperative and postoperative scotopic pupil sizes were measured by 2 examiners (E1, E2) with both a handheld light amplification pupillometer (Colvard, Oasis Medical, Glendora, CA) and a digital infrared pupillometer (Eye World Pupillometer [EWP], Oculus Keratograph, Oculus Opikgerate GmbH, Wetzlar, Germany). The agreement and interrater repeatability were determined using the comparison method described by Bland and Altman. The paired Student's t test was used to evaluate the difference between the preoperative and postoperative measurements. MAIN OUTCOME MEASURES: Scotopic pupil diameter, topographic corneal refractive power, uncorrected visual acuity (VA), best spectacle-corrected VA, and manifest spectacle refraction. RESULTS: The preoperative mean scotopic pupil diameter was 6.12+/-0.90 mm with the EWP and 6.18+/-0.91 mm with the Colvard. After the surgery, mean SE refractions were -0.22+/-0.98 D (myopic patients) and +0.19+/-0.40 D (hyperopic patients). Postoperative mean scotopic pupil diameters were 6.12+/-0.89 mm (EWP) and 6.17+/-0.90 mm (Colvard). There was no statistically significant difference between preoperative and postoperative mean scotopic pupil sizes in either patient group. The limits of agreement between the 2 devices ranged from 2.24 mm (E1) to 2.12 mm (E2) preoperatively and from 2.27 mm (E1) to 2.08 mm (E2) postoperatively. The coefficient of interrater repeatability ranged from 0.56 mm (EWP) to 1.12 mm (Colvard) preoperatively and from 0.62 mm (EWP) to 1.14 mm (Colvard) postoperatively. CONCLUSIONS: The digital infrared pupillometer showed better preoperative and postoperative repeatability than the handheld light amplification pupillometer. In the present study, a mean correction of <3 D of the corneal refractive power did not seem to modify the preoperative scotopic pupil size measurements.

Adult↗
PubMed2005

Improved safety in contemporary LASIK.

PURPOSE: To examine the risk of serious visual loss in contemporary LASIK. DESIGN: Retrospective, noncomparative, consecutive case series combined with a structured literature review and comparison with historical controls. PARTICIPANTS: One thousand consecutive cases of LASIK performed from January 2000 to January 2004 by 1 surgeon. One thousand nine hundred eighty-two cases with 6-month review data in postmillennial Food and Drug Administration (FDA) trials of LASIK for myopia and astigmatism and 5203 patients with 6 month review data in similar premillennial FDA trials. METHODS: LASIK was performed with the Hansatome microkeratome and a VISX Star (S2, S3, or S4) laser. There were 899 myopic treatments (spherical equivalent < or =-10.5 diopters [D]; average -4.2 D; standard deviations [SD] D = 1.9 D; astigmatism < or =4.75 D), 87 hyperopic treatments (spherical equivalent < or =+4.25 D; average +2.4 D; SD = 0.9 D; astigmatism < or =3.5 D), and 14 treatments for mixed astigmatism (< or =4.5 D). Outcome data were obtained from a review of case notes and compared with historical data from FDA trials. MAIN OUTCOME MEASURES: Best-spectacle corrected visual acuity (BSCVA) preoperatively and at final review was compared in our case series with reference to the United Kingdom driving standard (BSCVA> or =20/30). Subsidiary outcome measures included duration of follow-up, intraoperative, and postoperative complication rates. Six-month postoperative data on standard safety criteria (numbers of patients losing > or =2 lines BSCVA, BSCVA <20/40, and final BSCVA <20/25 for patients with preoperative BSCVA > or =20/20) were examined in FDA trials. RESULTS: In our clinical series, no case with a preoperative BSCVA of 20/20 or better had a final BSCVA of <20/30 at final review (97.5% confidence interval [CI], 0%-0.37%); 4 eyes had a BSCVA <20/25 (0.41%; 95%CI, 0.11%-1.02%). The median interval between surgery and final review was 2 months (range, 1-45 months). In FDA studies recruiting pre-2000, 1.4% of patients lost > or =2 lines of BSCVA versus 0.6% in postmillennial studies (P = 0.005); 0.45% of patients in premillennial studies lost BSCVA to <20/40 compared with no patients in postmillennial studies (P = 0.001); and 1.68% of patients in premillennial studies with a preoperative BSCVA > or =20/20 had a postoperative BSCVA <20/25 compared with 0.16% in postmillennial studies (P< or =0.001). CONCLUSIONS: Compared with premillennial results, the risk of visual loss is significantly reduced in contemporary LASIK.

Adult↗