Severe Myopia Research Articles

Myopia in infants treated for retinopathy of prematurity: the first year of life

Premature birth is associated with an increase in incidence of refractive errors. Cryotherapy for threshold retinopathy of prematurity further increases risk of developing high myopia. It was our clinical impression that a change in treatment to laser resulted in less severe myopia. We undertook a longitudinal study to determine the refractive outcome of each therapy. A total of 19 patients undergoing cryotherapy and 14 patients undergoing laser treatment, had cycloplegic refractions at corrected ages of three months and one year. At 3 months the median spherical equivalent refractive error in the right eye was −3.25 dioptres after cryotherapy and +0.25 dioptres after laser therapy. At twelve months it was −5.25 dioptres following cryotherapy and −0.50 dioptres after laser. The results for the left eye were comparable. The difference between the median spherical refractive error for the two treatment groups were significant at three months and twelve months (p > 0.05 Wilcoxon rank sum). Laser therapy is associated with lower degrees of myopia during the first year of life.

Myopia in infants treated for retinopathy of prematurity: the first year of life

Premature birth is associated with an increase in incidence of refractive errors. Cryotherapy for threshold retinopathy of prematurity further increases risk of developing high myopia. It was our clinical impression that a change in treatment to laser resulted in less severe myopia. We undertook a longitudinal study to determine the refractive outcome of each therapy. A total of 19 patients undergoing cryotherapy and 14 patients undergoing laser treatment, had cycloplegic refractions at corrected ages of three months and one year. At 3 months the median spherical equivalent refractive error in the right eye was −3.25 dioptres after cryotherapy and +0.25 dioptres after laser therapy. At twelve months it was −5.25 dioptres following cryotherapy and −0.50 dioptres after laser. The results for the left eye were comparable. The difference between the median spherical refractive error for the two treatment groups were significant at three months and twelve months (p > 0.05 Wilcoxon rank sum). Laser therapy is associated with lower degrees of myopia during the first year of life.

Excimer Laser Photorefractive Keratectomy for High Myopia: Four-year Experience with a Multiple Zone Technique

The purpose of the study is to evaluate the results of the authors' 4-year experience with excimer laser photorefractive keratectomy (PRK) and multiple optical zone corneal ablation in highly myopic eyes. The authors retrospectively evaluated 56 eyes of 44 patients (mean refraction, -11.3 diopters [D]; range, -5.75 to -24.5 D) who underwent PRK with a Visx Model 20/20 laser (Visx, Santa Clara, CA). Preoperative visual acuity of 20/40 or better was present in 46 eyes. Corneal ablation was divided into concentric optical zones (4, 5, and 6 mm), allowing corrections of up to 18 D, with a refractive goal of within -1 D from emmetropia in 49 eyes. A hand-held fixation system was always used, and a nitrogen-blowing system (NBS) was used in the first 21 eyes only. Before retreatment, the range of final cycloplegic refraction from emmetropia in eyes treated with NBS versus not was within +/-1 D in 6 (28.6%) and 15 eyes (44.1%), between -1.25 and -3 D in 5 (23.8%) and 14 eyes (41.1%), and more than -3 D in 10 (47.6%) and 5 eyes (14.7%), respectively. No lines of visual acuity were lost in 37 eyes (80.4%) with 20/40 or better visual acuity before surgery. Three eyes showed vision loss due to worsening of myopic maculopathy and one due to corneal haze. Correction stabilized within 9 months, and at a mean time of 25.6 months, the correction attained was of -8.5 +/- 3.6 D, achieving 90.3% of attempted correction. Eyes with preoperative myopia less than -10 D (n = 27) showed regression less than -1 D in 8 eyes (29.6%), between -1.25 and -3.00 D in 5 eyes (18.5%), and greater than -3.00 D in 1 eye (3.7%); eyes with more than -10 D (n = 29) regressed in 3 (10.3%), 6 (20.7%), and 1 eye (3.4%), respectively. Severe haze was observed in 11 eyes (19.6%) 3 months after surgery. Two eyes showed decentration greater than 1.5 mm. At last examination, night driving problems were reported by 12 (41.4%) of 29 patients evaluated who drive. After the NBS was eliminated, the multiple-zone technique achieved a long-term, stable 83.1% reduction of preoperative myopia. Patients with severe myopia appreciated reduction of most of the refractive defect, although perception of halos was noted by 16 patients.

A novel pattern of oculocerebral malformation

AIMS/BACKGROUNDTo report a novel pattern of oculocerebral malformation related to the group of diseases characterised by cobblestone lissencephaly.METHODSBy means of a case report with specialist descriptions of the novel neuropathological...

Indocyanine Green Angiography of Retrobulbar Vascular Structures in Severe Myopia

To evaluate angiographic findings of retrobulbar arteries and veins in severely myopic patients. We examined 416 severely myopic eyes (213 patients) with refractive errors greater than -8.25 diopters using indocyanine green videoangiography. A control group of 74 eyes (37 patients) had refractive errors within plano +/- 3 diopters. Four severely myopic patients underwent computed tomographic angiography to identify the entire intraorbital course of retrobulbar veins. Of 416 severely myopic eyes, 231 (55.5%) exhibited retrobulbar arteries, which were tortuous and pulsatile behind the posterior pole of the globe. Retrobulbar arteries connected directly with choroidal arteries temporal to the macular area. In 17 of these 231 eyes, retrobulbar arteries were also observed nasal to the optic nerve head, continuous with the Zinn-Haller ring around the optic nerve head and directly connected with choroidal arteries. In 39 severely myopic eyes (31 patients), indocyanine green angiography disclosed retrobulbar veins, most of which coursed vertically just behind the posterior pole of the globe. These retrobulbar veins originated as an inferior vascular network of the inferior orbital vein and drained into the superior orbital vein in the upper orbit. Retrobulbar arteries observed in this study were temporal and nasal short posterior ciliary arteries. Only the lateral collateral vein, which was one of the collateral channels between the superior and inferior orbital veins, was visible in severely myopic eyes. Indocyanine green angiography is useful in evaluating retrobulbar vascular structure in severely myopic eyes.

Severe Myopia as a Risk Factor for Progressive Visual Field Loss in Primary Open-Angle Glaucoma

The optic nerve head in severely myopic eyes may be particularly vulnerable to glaucomatous damage. To study this hypothesis, we examined 122 primary open-angle glaucoma eyes with fair to good control of the intraocular pressure and a sign of baseline optic nerve damage. Then, parameters for the progression of the visual field defects were evaluated by multivariate analysis. A high mean intraocular pressure (p = 0.007) and a large refractive error (p = 0.023) were significant risk factors for subsequent visual field loss. A high baseline cup-to-disk ratio (p = 0.100) was a marginal risk factor. Nonsignificant parameters included patient age (p = 0.692), the use of beta-adrenergic antagonists (p = 0.384), gender (p = 0.831) and left versus right side (p = 0.977). When the refractive error was used to subclassify patients into severely myopic (< or = -4 dpt), mildly myopic (-0.25 to -4 dpt), or emmetropic and hyperopic (> or = 0 dpt), only severe myopia was a significant risk factor for progressive visual field loss. Severe myopia, but not mild myopia, is a significant risk factor for subsequent visual field loss in patients with primary open-angle glaucoma.

Comparison of corneal sensation following photorefractive keratectomy and laser in situ keratomileusis

Purpose: To evaluate the effect of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) on corneal sensation.Setting: Eye Institute, Medical School of the University of Crete, Heraklion, Greece, and Orasis, Hellenic Eye Center of Athens, Greece.Methods: In a masked study, corneal sensation was measured with the CochetBonnet aesthesiometer in 40 consecutive patients 6 to 12 months following PRK and LASIK (60 mm constitutes normal reading and <40 mm, abnormal).Results: After 6 to 12 months, the mean corneal sensation following PRK was 39.2 mm (range 30 to 55 mm) (mean 9.5 months) and after LASIK, 53.6 mm (range 40 to 60 mm) (mean 9.3 months). The mean correction attempted for PRK was 7.05 diopters (D) (range 2.5 to 12.0 D) and for LASIK, 11.71 D (range 6.0 to 20.0 D).Conclusion: In this group of patients, with correction of primarily severe myopia, corneal sensation was significantly greater after LASIK than after PRK.

Undercorrection After Excimer Laser Refractive Surgery

The incidence and correlations of undercorrection were studied for 1 year after excimer laser surgery for myopia or myuopic astigmatism. A consecutive series of 645 eyes of 440 patients were studied. Eyes were examined preoperatively and at 1, 3, 6, and 12 months after surgery. The parameters evaluated were visual acuity, refraction, and corneal clarity. Following excimer laser surgery, undercorrection of > or = -1.00 diopters gradually increased from 10% at 1 month to 40% at 12 months. Increasing degree of preoperative myopia was significantly associated with increasing occurrence of undercorrection at 3 months (chi 2 = 17.3, P < .001), 6 months (chi 2 = 53.6, P < .001), and 12 months (chi 2 = 64.8, P < .001). Undercorrection was more common in eyes that had had photorefractive keratectomy than in those that had had photoastigmatic refractive keratectomy (odds ratio, 0.40; 95% confidence interval, 0.25 to 0.60). At 1 year, a loss of 2 or more lines of best-corrected visual acuity was recorded in 38% of undercorrected patients. Loss of 2 or more lines of best-corrected visual acuity was more common in patients undercorrected by -1.00 diopter or more (odds ratio, 8.8; 95% confidence interval, 5.4 to 14.6). No relationship was seen between corneal haze and loss of best-corrected visual acuity. Undercorrection was not associated with age, gender, use of nonsteroidal anti-inflammatory drugs, bandage contact lens wear, or corneal haze. Patients with lower degrees of myopia reached a stable refraction more quickly. At 6 months, 71% were within +/- 0.5 diopter of 1-year refraction. Of 17 patients with undercorrection who were treated with topical corticosteroids, only one patient showed a permanent beneficial change. Occurrence of undercorrection is more common in patients with severe myopia and when simultaneous astigmatic corrections are undertaken.

Long-term results of clear lens extraction for severe myopia

Purpose: To evaluate the efficacy and safety of clear lens extraction in the management of severe myopia.Setting: Seoul National University Hospital, Seoul, Korea.Methods: This retrospective study comprised 24 eyes of 16 patients who had clear lens extraction to treat myopia of 12.00 diopters (D) or more. A scleral pocket incision and continuous curvilinear capsulorhexis were made followed by lens extraction by phacoemulsification and low-power posterior chamber intraocular lens implantation. Mean follow-up was 15 months.Results: Fifteen eyes (62.0%) were within 1.00 D of targeted refractive error postoperatively; 22 (91.7%) were within +2.00 D. Uncorrected visual acuity improved in all eyes. All except 1 (95.8%) gained two or more Snellen lines. Best corrected visual acuity improved in 20 eyes (83.3%); 15 (75.0%) gained two or more lines. Best corrected visual acuity after surgery was 20/40 or better in 19 eyes (79.2%), a 37.5% increase over the preoperative number. Posterior capsule opacification developed in 1 eye; a neodymium:YAG laser posterior capsulotomy was performed at 4 months postoperatively. No retinal breaks, retinal detachments, or cystoid macular edema were observed during the follow-up.Conclusion: Clear lens extraction was effective in correcting severe myopia; however, longer follow-up of a large number of cases is needed to fully assess possible complications.

Retrephination keratoplasty for high astigmatism after penetrating keratoplasty.

We report preliminary results of a new procedure for correcting high astigmatism after penetrating keratoplasty. The procedure entails full-thickness trephination along the original donor-recipient junction with careful suturing in a combined interrupted and running fashion. Four eyes of four patients with severe astigmatism and myopia after penetrating keratoplasty underwent the procedure. High preoperative cylinder ranging from 4.50 to 16.00 D (mean 9.00 D) was reduced to 0.50 to 3.50 D (mean 1.90 D) at the last examination (between 3 to 6 months). Spherical equivalent myopia ranging from -2.00 to -10.25 D (mean -4.90 D) was essentially unchanged at plano to -9.00 D (-4.70 D) at the last examination. Overall, there was a mean refractive cylinder reduction of 7.10 D (79%). Retrephination after penetrating keratoplasty appears to be an acceptable alternative for correcting high astigmatism, and had only a small effect on the level of myopia.

Scleral buckling surgery in stage 4 retinopathy of prematurity.

Technical advances in neonatal intensive care have significantly increased the number of very low birth-weight babies that survive the perinatal period. Some of these infants develop severe retinopathy of prematurity that may lead to retinal detachment. Between November 1988 and January 1994, 28 eyes from 15 preterm babies underwent scleral buckling for stage 4 retinopathy of prematurity at a mean age of 4.2 months. Cryotherapy was performed preoperatively on 12 eyes and intraoperatively in the remaining 16 eyes. The mean follow-up period was 35 months. Scleral buckling produced retinal reattachment in 13 eyes (46.4%). Severe myopia (-5 D to -15 D) was found in all 13 of these eyes, 12 also presented convergent strabismus. Mean visual acuity, measured in 6 eyes from children over the age of 3 years was 20/40. In 7/28 eyes of the younger children of this group we found a fix and follow the light capability. No light perception was detected in 11/28 eyes; in the remaining 4/28 eyes there was only light perception. Scleral buckling failed to prevent the progression to stage 5 in 15 eyes (53.6%). Additional surgery was excluded for 9 of these eyes based on ultrasonography findings; the other 6 eyes underwent vitrectomy, which led to macular reattachment in 4 cases. Clinical experience shows that scleral buckling is not always capable of preventing progression of the disease to stage 5. Furthermore, even when the anatomic results of this procedure are good, the functional outcome is often complicated by severe visual impairment.

Retinal Detachments by Squash Ball Accidents

To evaluate the characteristics of retinal detachments caused by squash ball accidents. Twenty-six patients had a retinal detachment after a squash ball hit their eyes. Characteristics of the 26 eyes with retinal detachment were large retinal tears parallel to the corneoscleral limbus located close to the ora serrata usually in the temporal superior fundus quadrant (in 14 [54%] of the 26 eyes) and in the temporal inferior quadrant (in seven eyes [27%]); primarily intact vitreous with a traumatic avulsion of the vitreous base in approximately one half the patients; relatively slow progression of the retinal detachment; and additional damage to the choroid and retinal pigment epithelium in the posterior fundus. The patients were young and did not have severe myopia. Reattachment of the retina was achieved in 22 (85%) of the 26 patients. In 11 patients (42%), visual acuity outcome was 20/40 or better with best correction. Retinal detachments after squash ball accidents show different characteristics with worse prognosis than do ordinary rhegmatogenous detachments. Protective eyewear should be worn when playing squash.

PCR assay confirms diagnosis in syndrome with variably expressed phenotype: mutation detection in Stickler syndrome.

Stickler syndrome is an autosomal dominant disease with ocular (severe myopia, vitreal degeneration, and retinal detachment) and other systemic manifestations (hearing loss, cleft palate, epiphyseal dysplasia, and premature osteoarthritis). As...

Astigmatic Keratotomy Combined With Myopic Keratomileusis In Situ for Compound Myopic Astigmatism

Myopic keratomileusis in situ by an automated microkeratome corrects myopia but not astigmatism, which is traditionally corrected by astigmatic keratotomy months after keratomileusis. We developed a technique for simultaneously correcting astigmatism and severe myopia, and examined its effectiveness in a retrospective case-control study. Thirty-four eyes (23 patients) underwent myopic keratomileusis in situ combined with one or two arcuate keratotomy incisions performed after the refractive cut, in the bed of the primary keratectomy flap. The myopic keratomileusis control group consisted of 34 matched eyes (30 patients) undergoing keratomileusis without astigmatic keratotomy. The astigmatic control group consisted of 117 unmatched eyes (85 patients) undergoing astigmatic keratotomy combined with radial keratotomy. Mean refractive astigmatism in the study group decreased from 2.4 diopters (range, 1.0 to 4.0 diopters) preoperatively to 1.7 diopters (range, 1.0 to 4.0 diopters) at three months postoperatively, and increased by 0.4 diopter in the myopic keratomileusis control group at three months postoperatively (P < .005). Eighteen of 27 eyes in the study group showed decreased refractive astigmatism compared with ten of 34 eyes in the myopic keratomileusis control group (P < .0001). Combining astigmatic keratotomy with myopic keratomileusis produced 0.2 +/- 0.9 diopter less astigmatic correction than that expected from the astigmatic control group. One of 27 eyes lost two or more lines of best spectacle-corrected visual acuity at the three-month postoperative visit. No eye lost two or more lines of best spectacle-corrected visual acuity at postoperative month 6. Eyes with substantial preoperative refractive astigmatism that undergo myopic keratomileusis in situ may benefit from simultaneous astigmatic keratotomy to reduce residual post-operative refractive astigmatism.

Clinical results of excimer laser photorefractive keratectomy: A multicenter study of 265 eyes

Efficacy, predictability, and safety of excimer laser photorefractive keratectomy were evaluated at centers in Paris and Brest, France. Photoablation was performed with the VISX laser on 265 eyes (151 at the Paris center and 114 at the Brest center). The eyes were clinically and statistically evaluated over a six month follow-up. Initial myopia ranged from −0.7 to −19.4 diopters (D) (mean spherical equivalent [SE] −5.9 D) in the Paris center and from −0.9 to −14.5 D (SE −4.5 D) in the Brest center. At both centers, the mean uncorrected visual acuity was worse than 20/200; over 90% of cases in each center had a best uncorrected visual acuity of 20/100 or worse. Results are reported globally and for subgroups of myopia: Group A, SE better than or equal to −3.0 D; Group B, SE worse than −3.0 D and better than or equal to −7.0 D; Group C, SE worse than −7.0 D. Uncorrected visual acuity was significantly improved in the patients followed for six months; 64% of Paris cases and 62% of Brest cases obtained an uncorrected visual acuity of 20/40 or better. Predictability of the treatment was good; 67% of Paris eyes and 74% of Brest eyes were less than 1.0 D from the intended correction after six months. The data suggest that the initial myopia affected the efficacy and predictability of the treatment; results in the mild to moderate myopia eyes were significantly better than results in the severe myopia eyes. One case of visual acuity regression (less than one line) was observed in the two groups. This was associated with corneal haze of moderate intensity.

The relationship of choroidal blood flow and accommodation to the control of ocular growth

We have carried out a number of different studies in chicks to examine the relationship between choroidal blood flow and myopic eye growth, and between accommodation and myopic eye growth. Our studies on choroidal blood flow show that myopic eye growth produced by form vision degradation leads to dramatic reductions in choroidal blood flow. These reductions appear directly attributable to the eye enlargement and the reduction in choroidal blood flow does not appear to be permissive for eye growth, since experimentally reduced choroidal blood flow hinders eye growth. Choroidal blood flow that is slightly above normal, however, may slightly enhance eye growth. Our studies on accommodation do not reveal any major necessary role of accommodation in regulating normal growth or in form vision degradation induced myopic eye growth. We found preliminary evidence, however, that chronically stimulating accommodation over a 2 week period, thereby producing excessive time in accommodation, may be sufficient for yielding a small but significant degree of myopic refractive error. Our studies suggest that neither fluctuations in choroidal blood flow nor an intact accommodative apparatus are essential for normal eye growth or myopic eye growth produced by form deprivation. Further studies are needed to confirm that excessive time in accommodation might be sufficient for producing myopia. Finally, our finding that choroidal blood flow is substantially reduced in myopic eyes may have implications for the etiology of the retinal problems suffered by humans with moderate to severe myopia.

Clinical Analysis of Excimer Laser Photorefractive Keratectomy Using a Multiple Zone Technique for Severe Myopia

In an investigational procedure, excimer laser photorefractive keratectomy for severe myopia was performed at three clinical trial centers to determine the effectiveness of the multiple zone technique. A VisX Model Twenty/Twenty excimer laser (VisX, Santa Clara, California) was used to perform photorefractive keratectomy on 14 severely myopic eyes (-10.37 to -24.5 diopters) of 12 patients by using a multiple zone technique. Postoperative follow-up ranged from six months to two years; retreatments were performed on four patients, with a follow-up of at least nine months. At six months postoperatively, before retreatment, three of the 14 eyes were within 2 diopters and seven of the 14 eyes were within 4 diopters of attempted correction. Regression of effect to more severe myopia was worse in five eyes treated with nitrogen gas blowing. Retreatments also demonstrated considerable myopic regression. Three patients had loss of two or more lines of best-corrected visual acuity, and these patients also had moderate or severe levels of haze. Excimer laser photorefractive keratectomy for severe myopia using a multiple zone technique is associated with considerable regression, haze, and loss of best-corrected visual actuity, especially when performed in association with nitrogen gas blowing.

Myopia and stature: findings in a population of 106,926 males.

We conducted a nation-wide study of the relationship of myopia with height, weight and body-mass index in order to confirm observations that myopic persons are taller than non-myopes. From a review of the data of 106,926, consecutive male military recruits aged 17 to 19 years, we found that myopia is associated neither with higher stature nor with greater weight. Persons with severe myopia were slightly shorter (172.8 +/- 7.1 cm) and weighed less (62.6 +/- 11.0 kg) than those with mild myopia (173.3 +/- 6.9 cm and 63.8 +/- 10.5 kg respectively), while the non-myopes were taller (173.7 +/- 6.7 cm) and heavier (63.9 +/- 10.2 kg) than the myopes (p = 0.0001). The mean body-mass index was only slightly smaller among the myopes (21.1 +/- 3.1 kg/m2) than among the non-myopes (21.2 +/- 2.9 kg/m2, p = 0.0001).

Fluorophotometry in Myopic Phakic Eyes With Anterior Chamber Intraocular Lenses to Correct Severe Myopia

Implanting an anterior chamber intraocular lens in a phakic eye is an effective surgical procedure for the correction of severe myopia. However, the potential risks on the anterior segment structures are scarcely known. We conducted a prospective study to evaluate the permeability of the blood-aqueous barrier and the lens transmittance changes after Worst-Fechner lenses were implanted to correct myopia. Preoperative and serial postoperative fluorophotometry was done in 15 eyes that had a Worst-Fechner lens implanted to correct myopia. Lens transmittance was evaluated by lens autofluorescence, and permeability of the blood-aqueous barrier was estimated by anterior vitreous fluorophotometry, which was carried out before and after intravenous injection of fluorescein. Preoperative lens transmittance was 0.971 +/- 0.002 (mean +/- standard error), and, after the operation, lens transmittance decreased to 0.970 +/- 0.002 at one month, 0.966 +/- 0.001 at three months, 0.964 +/- 0.002 at six months, and 0.962 +/- 0.003 at 14 months. At three, six, and 14 months after the operation, lens transmittance values were significantly lower than preoperative values (P = .038 at three months, P < .001 at six months, and P = .005 at 14 months). Fluorescein concentration in the anterior vitreous was 18.522 +/- 1.797 ng/ml (mean +/- standard error) preoperatively and was 21.328 +/- 1.667 ng/ml at one month, 27.518 +/- 1.412 ng/ml at three months, 27.150 +/- 1.474 ng/ml at six months, and 27.012 +/- 1.980 ng/ml at 14 months postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

193-nm Excimer Photorefractive Keratectomy in High Myopia

To evaluate the refractive results of 193-nm excimer laser photorefractive keratectomy (PRK) performed on 48 highly myopic eyes in a multicenter study. A Visx 2015 or 2000 argon-fluoride excimer laser and a single-zone ablation technique were used. Postoperatively, eyes were treated with topical fluoromethalone for up to 5 months. Most eyes were treated with a 6.0- to 6.2-mm beam diameter after undercorrections and increased regression were noted with a 5.5-mm beam in earlier studies. Forty-eight eyes were treated for myopia, which was between -8.0 and -15.25 diopters (D) (spherical equivalent). The mean preoperative refraction was -11.2 D. Retreatment was performed after 6 to 16 months on 11 eyes for undercorrection. All eyes not retreated were followed for at least 12 months. At 6 months, follow-up was available on 47 eyes. Of these eyes, 40% and 64% achieved corrections within 1 and 2 D of attempted correction, respectively. At 1 year, 60% of eyes attained 20/40 visual acuity or better uncorrected. Eleven patients (23%) were retreated between 6 to 16 months for undercorrection and/or regression. After retreatment, 47% and 81% of eyes achieved corrections within 1 and 2 D of attempted correction, respectively. At 1 year, 15% of eyes lost two lines of best-corrected visual acuity, and no eyes lost more than two lines. There was slightly more corneal haze seen in this group compared with the haze seen in patients undergoing PRK for low and moderate myopia. These data show that excimer PRK can correct high amounts of myopia with reasonable stability after 6 months. Excimer PRK is an effective surgical treatment of severe myopia, but long-term follow-up is still needed to assess the stability of its effect.