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Evaluation of inner retinal function in myopia using oscillatory potentials of the multifocal electroretinogram.

PURPOSE: Oscillatory potentials have been suggested to arise from the inner retina at the level of amacrine cells and inner plexiform layer and they are thought to provide a non-invasive assessment of inner retinal function. We sought to investigate the response dynamics of the inner retina of adult emmetropes and myopes by analysing the oscillatory potentials of the multifocal electroretinogram (mfERG) in these groups. METHODS: Eleven emmetropes and 18 myopes underwent mfERG testing using VERIS 5.1.5X. Myopes were further separated based on whether their myopia was stable (n=9) or progressing (n=9). Oscillatory potentials were recorded using a modified mfERG stimulation technique, the slow flash paradigm, and they were extracted using band-pass filtering from 100 to 300 Hz. The slow flash mfERG stimulus array consisted of 103-scaled hexagons and flickered according to a pseudorandom binary m-sequence (2(13)-1). Amplitudes and implicit times of the first-order oscillatory potentials were analysed. RESULTS: There were significant differences in the implicit time of the oscillatory potentials of the emmetropes, stable myopes and progressing myopes (F(2,25)=3.663, p=0.043). Progressing myopes had significantly shorter implicit times compared to emmetropes (p=0.026 by 1.0-4.7 ms) and stable myopes (p=0.043 by 0.8-1.3 ms), whereas implicit times of stable myopes and emmetropes were similar. There were no statistically significant differences in amplitude of the oscillatory potentials between the groups (F(2,25)=0.890, p=0.426). CONCLUSIONS: Significant differences in multifocal oscillatory potentials between stable and progressing myopes were found. This finding is further evidence of an inner retinal involvement in human myopia progression and may suggest an underlying alteration to dopaminergic or GABAergic retinal systems.

Adolescent↗

Comparison of visual results in initial and re-treatment laser in situ keratomileusis procedures for myopia and astigmatism.

PURPOSE: To report the results of initial and re-treatment laser in situ keratomileusis procedures for myopia and astigmatism. METHODS: A total of 1161 consecutive inital and retreatment laser in situ keratomileusis procedures in 697 patients performed between September 19, 1996, and June 20, 1998, were retrospectively analyzed. Baseline and postoperative best spectacle-corrected visual acuity, uncorrected visual acuity, spherical and cylindrical refractions, computerized video keratography, and biomicroscopy were measured or performed on each eye. RESULTS: Of 1,071 eyes, 900 (84%) underwent a single-laser in situ keratomileusis procedure, and 171 of 1,071 eyes (16%) underwent one or two re-treatment procedures. The preoperative mean +/- SD spherical equivalent was -5.09 +/- 3.15 diopters (range, -0.75 to -14.38 diopters) and the cylinder was 0.97 +/- 1.09 diopters (range, 0.00 to 3.25 diopters) in the group that underwent a single laser in situ keratomileusis treatment. The preoperative mean +/- SD spherical equivalent was -6.26 +/- 3.04 diopters (range, -1.75 to -12.88 diopters) and the cylinder was 1.53 +/- 1.11 diopters (range, 0.00 to 3.50 diopters) in the group that underwent re-treatment. Before re-treatment, 110 eyes (64.3%) in the group that underwent re-treatment achieved 20/40 or better uncorrected visual acuity and 23 eyes (13.5%) achieved 20/25 or better. Three months after re-treatment, 155 eyes (90.6%) achieved 20/40 or better, and 80 eyes (46.8%) achieved 20/25 or better. In the single-procedure group, uncorrected visual acuity at 3 months revealed 20/40 vision or better in 856 eyes (95.1%) and 20/25 vision or better in 572 eyes (63.6%). In this study group, 23.6% of eyes with a preoperative spherical equivalent greater than -6.0 diopters underwent re-treatment compared with 11.8% of eyes with a preoperative spherical equivalent of -6.0 diopters or less. CONCLUSIONS: Laser in situ keratomileusis appears to be an effective procedure for mild, moderate, and severe myopia. In eyes with residual refractive error, re-treatment laser in situ keratomileusis procedures can result in good visual outcomes.

Astigmatism↗

Translocation of the macula for management of subfoveal choroidal neovascularization: comparison of results in age-related macular degeneration and degenerative myopia.

PURPOSE: To report the results of limited macular translocation in subfoveal choroidal neovascularization resulting from age-related macular degeneration or degenerative myopia. METHODS: The first consecutive 32 patients (23 age-related macular degeneration eyes and nine myopic eyes) were operated on with the limited macular translocation technique described by de Juan. Before and after surgery, a complete examination included fluorescein and indocyanine-green angiographies and optical coherence tomography. Mean follow-up was 9 months in the age-related macular degeneration group (range, 6 to 14 months) and 10 months in the myopic group (range, 6 to 15 months). RESULTS: The improvement in visual acuity was better in the myopic group than in the age-related macular degeneration group and was correlated with younger age in the myopic group (P <.05). At the end of follow-up, visual acuity improved by 2 lines or more in seven age-related macular degeneration eyes (30%), including four eyes (13%) with an improvement of 6 lines or more, and in six myopic eyes (67%), including two eyes (22%) with an improvement of 6 lines or more. Final visual acuity was unchanged in four age-related macular degeneration eyes (17%) and three myopic eyes (33%), and decreased in 12 age-related macular degeneration eyes (52%). Conversely, the mean foveal displacement was greater in age-related macular degeneration than in myopia (1,105 microm and 685 microm, respectively; P <.05). Main complications were retinal detachment (six eyes), neovascularization at the injection site (two eyes), and recurrence of neovascularization (43% of the age-related macular degeneration group and 11% of the myopic group). CONCLUSIONS: Limited macular translocation allowed a significant improvement in visual acuity in some eyes with subfoveal neovascularization and resulted in a moderate rate of complications. Longer follow-up and additional studies are required to confirm these findings.

Adult↗

Laser in situ keratomileusis for treatment of residual myopia after photorefractive keratectomy.

PURPOSE: To evaluate the results of laser in situ keratomileusis after photorefractive keratectomy. METHODS: Eighty eyes of 80 patients with residual myopia after photorefractive keratectomy were reoperated with laser in situ keratomileusis. The study was retrospective. Laser in situ keratomileusis was performed using the automated corneal shaper microkeratome and Chiron Technolas 217-C d1 excimer laser. Data measured after laser in situ keratomileusis included uncorrected visual acuity, best-corrected visual acuity, refraction, haze, pachymetry, and keratometry. The follow-up was at least 12 +/- 1.6 months (range, 12 to 15 months). RESULTS: After laser in situ keratomileusis the mean spherical equivalent was -0.24 diopters +/- 0.78. (range, -3 to +1.5) at 12 months, and the mean uncorrected visual acuity was 0.76 diopters +/- 0.24 (range, 0.1 to 1). Sixty-five eyes (81.3%) had various degrees of haze after laser in situ keratomileusis. One eye (1.2%) lost 2 lines of best-corrected visual acuity. CONCLUSIONS: Laser in situ keratomileusis enhancement may be a good alternative to correct residual myopia and astigmatism after primary photorefractive keratectomy. Corneal haze is a common problem in these eyes, and the treatment after laser in situ keratomileusis enhancement should be the same as the treatment after primary photorefractive keratectomy.

Adolescent↗

Progressive axial myopia in a juvenile patient with traumatic glaucoma.

PURPOSE: To report a case of progressive axial myopia associated with traumatic glaucoma in a juvenile patient with no systemic disease. DESIGN: Interventional case report. METHODS: In a 15-year-old male, serial ocular examinations, including manifest refraction, tonometry, and axial eye length measurement, were performed over a 6-year period, beginning with blunt trauma, right eye, followed by a series of surgical procedures for traumatic cataract and glaucoma. RESULTS: A 4-diopter myopic shift (from -1.25 to -5.25) with a 1.5 mm increase in the axial eye length occurred, whereas the intraocular pressure increased from 21 to 46 mm Hg, during a 2-year period. The refraction, axial eye length, and intraocular pressure remained stable during the same period in the fellow, normal eye. CONCLUSION: Progressive axial myopia associated with traumatic glaucoma is possible in a juvenile patient in his late teens.

Adolescent↗

Angle-supported phakic intraocular lenses followed by laser-assisted in situ keratomileusis for the correction of high myopia.

To evaluate the safety, effectiveness, predictability, and stability of the combination of angle-supported phakic intraocular lens (PIOL) implantation and laser-assisted in situ keratomileusis (LASIK) for the correction of high myopia. Noncomparative interventional case series. At the Instituto Oftalmológico de Alicante, Spain, 24 consecutive eyes of 12 patients with a preoperative spherical equivalent between -9 and -26 diopters were studied. Implantation of an angle-supported PIOL was done as the first surgery. Laser-assisted in situ keratomileusis was performed at least 6 months after PIOL surgery, once stability of topography and refraction were proved. Main outcome measures were uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), refraction, applanation tonometry, and corneal endothelial study (cell density, hexagonality, and coefficient of variation), with a minimum follow-up of 12 months after LASIK. The mean spherical equivalent refraction decreased from -15.17 +/- 5.15 diopters before PIOL implantation to -1.33 +/- 1.18 diopters after PIOL surgery and to 0.01 +/- 0.53 12 months after LASIK. Uncorrected visual acuity was 0.39 +/- 0.12 after PIOL surgery, increasing to 0.65 +/- 0.23 12 months after LASIK. There was an increase in 20/40 or better UCVA from 16.6% after PIOL surgery alone to 83.3% after addition of LASIK. At final follow-up, spherical equivalent was within +/- 1 diopter of emmetropia in 22 eyes (91.7%) and in 18 eyes (75%) within +/- 0.50 diopters. Vector analysis demonstrated that astigmatic components of refractive error after PIOL surgery were well corrected by LASIK. At final follow-up the mean endothelial cell loss was 4.88% (P <.001). There were no statistically significant differences between mean endothelial cell count, percentage of hexagonality, or coefficient of variation before LASIK and 12 months after LASIK, suggesting that no corneal endothelial damage was produced by LASIK itself. No sight-threatening complications occurred through the follow-up period. The combination of angle-supported PIOL implantation and LASIK appears to be a safe, effective, predictable, and stable procedure for the correction of high myopia. This paper emphasizes the benefits of adding LASIK to the use of PIOL alone.

Adult↗

Mechanism of topiramate-induced acute-onset myopia and angle closure glaucoma.

DESIGN: Interventional case report. METHODS: In an institutional practice setting, two women, aged 25 and 45, developed acute myopia after starting topiramate for epilepsy. One patient also developed bilateral angle closure glaucoma. RESULTS: Topiramate was discontinued. Anterior chamber shallowing was noted in both patients at presentation. Ultrasonography showed ciliochoroidal effusion. Baseline measurements of anterior chamber depth and lens thickness were obtained. CONCLUSIONS: Topiramate may be associated with ciliochoroidal effusion with forward displacement of the lens-iris diaphragm and anterior chamber shallowing, resulting in acute myopia and angle-closure glaucoma. Increased lens thickness contributes only minimally (9%-16%) to anterior chamber shallowing.

Acute Disease↗

Indocyanine green angiographic features of pathologic myopia.

PURPOSE: To analyze indocyanine green angiographic findings of pathologic myopia and compare them with those of fluorescein angiography, with particular reference to the usefulness of indocyanine green angiography in the management of neovascular complications. METHODS: Thirty-two consecutive patients (52 eyes) with pathologic myopia underwent a complete ophthalmologic examination including fluorescein and indocyanine green angiography. RESULTS: Retrobulbar arteries and veins were visualized solely on indocyanine green angiography in 33 (63%) of 52 eyes. Choroidal arteries appeared attenuated and reduced in number. In the area of staphyloma, choroidal veins were less numerous, and in all eyes an absence of the normal choroidal flush caused by the choriocapillaris filling was observed. Subretinal and retinal hemorrhages were present in 28 (54%) of 52 eyes. Choroidal neovascularization was diagnosed in 16 eyes on fluorescein angiography and in 18 eyes on indocyanine green angiography. In seven eyes, indocyanine green angiography disclosed lacquer cracks (without choroidal neovascularization), appearing in the late phases as hypofluorescent lines, as the probable cause of the subretinal and retinal hemorrhages. In only one eye did indocyanine green angiography fail to disclose choroidal neovascularization detectable on fluorescein angiography. In two eyes, neither dye could clarify the origin of the hemorrhages. CONCLUSIONS: Indocyanine green angiography allows identification of retrobulbar arteries and veins, and analysis of the altered choroidal vasculature. Moreover, indocyanine green angiography is a useful diagnostic tool to differentiate lacquer cracks from choroidal neovascularization in retinal and subretinal hemorrhages.

Adolescent↗

Radial keratotomy for intolerable myopia after penetrating keratoplasty.

Radial keratotomy was used to treat intolerable myopia in nine patients aged 56 to 86 years who had previously undergone penetrating keratoplasty and intraocular lens placement. The degree of myopia ranged from -5.25 to -9.25 diopters spherical equivalent before radial keratotomy. An eight-cut radial keratotomy with either a 4.0- or 4.50-mm central clear zone was performed on all patients. One year after the radial keratotomy, the spherical equivalent ranged from -1.25 to +1.63 diopters, which rendered all patients spectacle tolerant. Endothelial cell counts done before and one year after radial keratotomy demonstrated no marked loss of endothelial cell density. No complications were seen as a result of the radial keratotomy.

Aged↗

Scleral buckling for rhegmatogenous retinal detachment associated with severe myopia.

From Jan. 1, 1980, to Dec. 31, 1989, we performed scleral buckling surgery on 48 eyes of 46 patients for rhegmatogenous retinal detachments associated with severe myopia (greater than 5.00 diopters). Forty eyes of 38 patients were observed for at least six months, and the mean follow-up period was 46 months. Intraoperative complications occurred in four of 48 eyes (8%) and included retinal incarceration (two eyes), choroidal hemorrhage (one eye), and choroidal detachment (one eye). Three of the 40 eyes (7.5%) followed up for more than six months developed a recurrent retinal detachment and underwent a revision of the scleral buckle. At the last follow-up examination, the retinas of all 40 eyes were totally reattached. Final visual acuity of 20/40 or better was attained in 26 of 40 eyes (65%). Because of the low rate of intraoperative complications and the high rate of success, scleral buckling is recommended for most patients with rhegmatogenous retinal detachments associated with severe myopia.

Adolescent↗

Prevalence of lattice degeneration and its relation to axial length in severe myopia.

We studied 436 eyes of 218 patients with myopia of -6.00 diopters or more in both eyes. Of 218 patients, 72 (33.0%) had lattice degeneration of the retina. Among these 72 patients, lattice lesions were uniocular in 39 (54.2%) and binocular in 33 (45.8%). Of 105 males, 33 (31.4%) had lattice degeneration; of 113 females, 39 (34.5%) had lattice degeneration. Contrary to previously published data, we found an inverse relationship between axial length and the prevalence of lattice degeneration in severely myopic eyes. The greatest prevalence of lattice degeneration (63 of 154 eyes, 40.9%) was found in eyes with an axial length of 26.0 to 26.9 mm (-6.00 to -8.70 diopters), and the least prevalence of lattice degeneration (five of 71 eyes, 7.0%) was found in eyes with an axial length of 32.0 mm (-24.00 diopters) or greater. This may explain the observation that retinal detachment after cataract surgery has been noted more commonly among patients with moderate than severe myopia.

Adolescent↗

Photorefractive keratectomy for myopia in the setting of adenoviral subepithelial infiltrates.

PURPOSE: To report a patient with persistent subepithelial corneal opacities 18 months after adenoviral keratoconjunctivitis who underwent photorefractive keratectomy for the correction of myopia. METHODS: Case report, review of medical literature, and slit-lamp photography. RESULTS: The patient underwent photorefractive keratectomy in each eye, 1 week apart, with ablation of central corneal opacities and resultant best-corrected visual acuity of BE, 20/20. Symptomatic subepithelial stromal infiltrates recurred in the peripheral but not the central cornea of each eye 3 months after laser treatment. CONCLUSIONS: Photorefractive keratectomy was successful in the correction of myopia and prevented the recurrence of adenoviral subepithelial corneal infiltrates within the laser-treated central cornea.

Adenovirus Infections, Human↗

Precrystalline posterior chamber intraocular lens for surgical correction of severe myopia.

PURPOSE: To report early experience with a posterior chamber precrystalline intraocular lens designed for correction of severe myopia from -10 to -30 diopters. This intraocular lens respects the transparent crystalline lens and does not interfere with accommodation. METHOD: The concave-convex methylmethacrylate lens, with flexible haptics that are supported in the sulcus, is placed behind the iris, in front of the lens, and centered with the pupil. RESULTS: From July 1995 to November 1998, 149 precrystalline lenses have been inserted with few, generally reversible complications, which are now largely prevented by adequate modification of the intraocular lens. Correction has been satisfactory and stable. CONCLUSION: Although follow-up is relatively short, precrystalline lens placement may be considered an important contribution to the surgical management of severe myopia to improve the patient's vision and, consequently, quality of life.

Adult↗

Retinal peripheral changes after laser in situ keratomileusis in patients with high myopia.

BACKGROUND: Retinal detachment has been reported after laser in situ keratomileusis (LASIK) in myopic eyes. This complication may be related to the risk from myopia before surgery or may be induced by LASIK surgery itself. We performed a study to evaluate retinal peripheral changes after LASIK in patients with high myopia and to correlate symptoms on presentation and vitreoretinal anatomic changes. METHODS: The study was carried out at a university-affiliated hospital in São Paulo between November 1997 and February 1999. Patients scheduled to undergo LASIK were included if their spherical equivalent was greater than 6.00 dioptres. The exclusion criteria were previous retinal treatment and myopic macular degenerations. We performed binocular indirect ophthalmoscopy with scleral indentation and fundus biomicroscopy with Goldmann lens before LASIK and 1, 3 and 6 months after surgery. RESULTS: We examined 198 eyes preoperatively. Of the 198, 50 did not undergo LASIK surgery owing to refractive criteria, and 79 were lost to follow-up. We thus studied 69 eyes. The mean spherical equivalent preoperatively was -8.00 D (standard deviation 1.95 D). Twenty-four eyes had normal retinal periphery preoperatively; all 24 remained without alterations after LASIK. Forty-five eyes had peripheral alterations: 17 (24.6%) had cystic degeneration, 14 (20.3%) had lattice degeneration, 11 (15.9%) had white-without-pressure, 5 (7.2%) had cystic tufts, 3 (4.3%) had pavingstone degeneration, 2 (2.9%) had pigmentary alteration, 1 (1.4%) had holes with free operculum, and 1 (1.4%) had punctiform holes. The only alteration after surgery was almost punctiform holes around the previous cystic tuft 1 month after surgery in one patient. Retinal detachment did not develop in any of the eyes. INTERPRETATION: In this group of patients it appears that LASIK did not lead to progressive peripheral retinal lesions in asymptomatic patients during the period studied.

Adult↗

Sex differences in chick eye growth and experimental myopia.

Stimulated by reported sex differences in eye size and refraction in humans, we compared refractions and ocular size measurements of male and female chicks. Chicks were reared under a 12-hr light/dark cycle with one eye open and the other occluded by a goggle or lid suture, each well-established means of inducing ipsilateral myopia. While the open eyes of the two sexes emmetropized equally well, both ultrasound and caliper measurements demonstrated that on average males have larger eyes. Although statistically significant for defined populations, the sex differences in open eyes were to small to be diagnostic for individual birds. The visually-deprived eyes of male chicks were more reactive than those of females, especially following deprivation by a goggle. Consistently, the anterior chamber of visually-deprived eyes of males was deeper than those of the females regardless of the means of impairing vision. With a goggle, males also developed more myopia and a deeper vitreous chamber than females similarly occluded. When goggles were removed, rapid recovery occurred in 2 weeks irrespectively of sex.

Animals↗

The effect of an interrupted daily period of normal visual stimulation on form deprivation myopia in chicks.

The aim of this study was to determine whether an integrator of neural activity influences the amount of myopia and axial elongation resulting from deprivation of form vision. The effects on ocular parameters of a continuous period of 30 min per day of normal vision was compared to two exposures of 15 min duration each, or three exposures of 10 min each. For the remaining time, chicks had monocular translucent occlusion in a 12 hr light/12 hr dark diurnal cycle, for either 2 or 3 weeks. Fellow eyes and the eyes of bilaterally unoccluded chicks were used as controls. We found that several short periods of normal visual stimulation per day were more effective in preventing the development of form deprivation myopia and axial elongation than was one single period of the same total duration, after both 2 and 3 weeks of treatment. This study suggests that the level of neural activity in the retina may have a cumulative effect in influencing ocular growth.

Animals↗

Corneal surface topography and associated visual performance with INTACS for myopia: phase III clinical trial results. The INTACS Study Group.

OBJECTIVE: To characterize corneal topography with INTACS (KeraVision, Inc., Fremont, CA) an ophthalmic device designed to correct myopia, and relate findings to visual performance. DESIGN: Prospective nonrandomized self-controlled comparative intervention study. PARTICIPANTS/INTERVENTION: Patients were participants in the INTACS FDA phase III clinical trials. MAIN OUTCOME MEASURES: Preoperative and postoperative month 6 videokeratographic corneal topography (EyeSys, Houston, TX) was analyzed for 165 eyes from eight clinical sites. Topographic flattening, asphericity, and surface characteristics were statistically evaluated for relationship to visual acuity, refractive data, contrast sensitivity, and subjective visual symptoms. RESULTS: Corneal radius of curvature flattening was aspheric in nature and increased incrementally and significantly for progressively thicker INTACS (P < 0.05). Comparative stratification analyses suggest potential interactions between existing preoperative asphericity and myopia, postoperative asphericity, and visual performance outcomes. Qualitative symmetric and asymmetric toric topography patterns were related to the postoperative self-reported visual symptoms of "double images" (P < or = 0.05) and "halos" (P < or = 0.10), respectively. CONCLUSIONS: The anterior corneal surface is aspherically flattened (prolately) with INTACS, whereas postoperative corneal asphericity is significantly more prolate than preoperative. Specific qualitative postoperative topography patterns were associated with subjective clinical visual performance.

Adult↗

Macular hole surgery in high myopia.

PURPOSE: To evaluate the anatomic and functional outcomes of macular hole surgery in high myopia and to determine whether surgery is beneficial in myopic eyes with macular holes. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: Twenty eyes of 18 highly myopic subjects who underwent pars plana vitrectomy for macular holes. METHODS: We analyzed demographics, preoperative, and postoperative characteristics in 20 eyes with macular holes with a mean of 10.4 months duration and myopia of 6 diopters or greater. MAIN OUTCOME MEASURES: Macular hole closure rate and mean visual acuity preoperatively and postoperatively. RESULTS: Mean subject age was 56.4 years and preoperative visual acuity was 20/100+2. The macular hole was closed with one surgery in 60.0% of eyes and in 85.0% of eyes with one or more surgeries. The mean final acuity in all eyes was 20/63, and 40.0% improved greater than three Snellen lines at the final visit. The use of adjunctive agents seemed to have no effect on macular hole closure or visual acuity. A subgroup of three myopic eyes with retinal detachments surrounding the macular hole had successful closure with visual acuity improvement in two of three eyes. CONCLUSIONS: Macular hole surgery can give substantial visual improvement in myopic eyes with macular holes, but the anatomic closure rates are lower than in eyes with idiopathic macular holes, and thus a higher reoperation rate is required.

Female↗