Surgical correction of hyperopia

Surgical attempts to correct hyperopia have yielded varying results over the last 130 years. These techniques include the reshaping of the cornea through incisions, burns, or lamellar cuts with removal of peripheral tissue; the addition of central inlays; laser ablations; and the replacement of the crystalline lens. By examining the success of each surgical technique, the refractive surgeon may be able to make an informed decision on its indications and limitations, based on the specific patient's characteristics. Reporting the outcomes and complications of hyperopic surgery will help refine our approach to the management of an increasingly hyperopic and presbyopic population.     

PermaVision intracorneal lens for the correction of hyperopia

PURPOSE: To evaluate the safety, predictability, and efficacy of sutureless synthetic keratophakia (SSK) with PermaVision intracorneal lens (Anamed) implantation. SETTING: Ophthalmic Hospital, Rome, Italy. METHODS: This retrospective study analyzed the refractive outcomes in 10 eyes of 6 patients who had SSK with PermaVision lens implantation for spherical hyperopia (cylinder less than 1.0 diopter [D]). Preoperatively, the mean spherical equivalent (SE) refraction was +4.33 D +/- 1.52 (SD) (range +3.00 to +6.37 D). All procedures were performed using the Hansatome microkeratome (Bausch & Lomb) with a superior hinge except in 1 eye in which the flap was cut using the Amadeus microkeratome (Allergan) with a nasal hinge. RESULTS: Six months after PermaVision lens insertion, the mean SE refraction was +0.03 +/- 0.36 D (range -0.50 to +0.38 D), the mean uncorrected visual acuity was 0.85 +/- 0.13 (range 0.63 to 1.00), and the mean best corrected visual acuity was 0.99 +/- 0.19 (range 0.63 to 1.25). No eye lost lines of visual acuity. In 1 eye, the lens was acutely decentered and had to be explanted. CONCLUSIONS: Sutureless synthetic keratophakia with the PermaVision intracorneal lens is a new technique for the correction of hyperopia. It is easy to perform as well as reversible, and the learning curve of the experienced laser in situ keratomileusis surgeon is short. The technique was safe and effective for spherical hyperopia, but longer follow-up and additional cases are needed to draw conclusions about the efficacy of the technique.     

Self-optimised vision correction with adaptive spectacle lenses in developing countries

It is estimated by the World Health Organization that about 1 billion people in the developing world would benefit immediately from distance vision and near vision correction if it were available to them. Here we address this problem and provide a solution by correcting vision in the field with adaptive liquid-filled variable focus lenses. We describe the details of the lens and present the results of a series of experiments performed in Ghana, Nepal, Malawi and South Africa that demonstrate that it is possible by simple means to self-determine and obtain correct refraction using such lenses.     

Rotated prism-wear disrupts emmetropization but does not reliably induce hyperopia in the New World monkey

To determine whether a disruption of binocular vision that has been previously shown to be amblyogenic disturbs visually guided growth, and in particular to follow-up the observation by Kiorpes and Wallman [Kiorpes, L., & Wallman, J. (1995). Does experimentally-induced amblyopia cause hyperopia in monkeys? Vision Research, 35(9), 1289-1297] that monkeys in whom strabismus had been induced some years earlier were hyperopic in eyes that had become amblyopic, we induced unilateral fixation in five infant New World monkeys (marmosets) through the wearing of a Fresnel prism (of 15 or 30 prism dioptres power) in front of one eye for four weeks. The prism was rotated every three hours during the prism-wear period to encourage a preference for fixating with the contralateral eye. Refractive error and intraocular axial dimensions were measured before, and at intervals after the prism-wearing period. Fixation preference was measured behaviourally, during and after the prism-wear period. Cortical visual function was subsequently assessed through recording of pattern-reversal VEPs in each marmoset between 11 and 14 months of age to assess whether amblyopia had developed in the non-fixing eye. All marmosets used the untreated eye almost exclusively for a monocular visual task by the end of the prism-rearing period. This preference was still present up to at least 7 months after prism-wear had ceased. VEP measures showed a loss of sensitivity at low spatial frequencies (the only ones we were able to test), compatible with amblyopia having developed in the non-fixating eyes of the prism-reared marmosets. Eyes that wore prisms were not significantly different from their fellow eyes in mean refractive error or mean vitreous chamber depth (repeated measures ANOVA; P>0.05) before or at any time after prism-wear had ceased. Two marmosets developed 2-3D of anisometropia (one hyperopic and one myopic) at the end of prism-wear, that was attributable to interocular differences in vitreous chamber depth, and which decreased towards isometropia in the period following prism-wear removal. Disruption of binocular vision with rotating prisms can influence emmetropization and ocular growth, although it does not appear to do so in a consistent way.     

Conductive keratoplasty for the correction of residual hyperopia after LASIK

PURPOSE: To report the 6-month results concerning efficacy, safety, predictability, and stability of conductive keratoplasty for the correction of residual hyperopia after corneal refractive surgery. METHODS: A total of 35 eyes (26 patients) with residual hyperopia after corneal refractive surgery ranging between +1.00 to +4.75 diopters (D) of spherical equivalent refraction were enrolled in the study and underwent conductive keratoplasty following a modified nomogram. RESULTS: Variables and data were available for all eyes at 6 months postoperatively. A total of 24 (69%) eyes had uncorrected visual acuity (UCVA) of > or = 20/40, and 10 (29%) eyes had UCVA of 20/20. Manifest refractive spherical equivalent was within +/- 0.50 D in 17 (49%) eyes and within +/- 1.00 D in 25 (71%) eyes in cases of previous hyperopic LASIK; the optical zone was significantly increased. CONCLUSIONS: Using a modified nomogram, conductive keratoplasty for correction of residual hyperopia was effective, but predictability was not satisfactory and safety needs to be established.     

Corneal suture for the correction of hyperopia following radial keratotomy

PURPOSE: To report the visual and refractive changes observed after double concentric corneal suture to correct hyperopic shift after radial keratotomy (RK). METHODS: This retrospective consecutive case series comprised 17 eyes (15 patients) that underwent two concentric corneal sutures (modified Grene Lasso suture) to correct hyperopic shift after RK. All surgeries were performed by the same surgeon between 2000 and 2003. RESULTS: The mean time after RK was 11.6 +/- 3.2 years. The mean follow-up was 20.3 +/- 11.3 months. The spherical equivalent refraction was reduced from a preoperative mean of +4.38 +/- 2.87 diopters (D) to -0.54 +/- 2.59 D at last postoperative follow-up (P < .001). No statistically significant difference was observed in mean refractive astigmatism before and after the corneal suture (P = .15). Before surgery, no eye presented with best spectacle-corrected visual acuity (BSCVA) > or = 20/20. At final follow-up, 3 (17.6%) eyes attained this level. Seven (41.2%) eyes improved their BSCVA by > or = 2 Snellen lines. One (5.9%) eye lost 2 Snellen lines of BSCVA. CONCLUSIONS: Corneal suture can be used to correct RK-induced hyperopia, improving the corneal asphericity in an attempt to stabilize these corneas. It appeared to be effective even for high degrees of hyperopia and in cases with associated irregular astigmatism or open incisions.     

远视足矫对屈光性调节性内斜视患者正视化的影响

目的 探讨屈光性调节性内斜视患者配戴完全远视矫正眼镜对正视化的影响.方法 临床病例对照研究.收集1990～1997年期间在中山大学眼科中心66例屈光性调节性内斜视和95例远视不伴有内斜的患儿进行回顾性调查研究.共计161例,322只眼,全部患者用1％Atropine睫状肌麻痹剂散瞳验光,将远视性屈光不正完全矫正的屈光性调节性内斜患者66例(132只眼)归为足矫组,远视性屈光不正部分矫正的普通远视患者95例(190只眼)归为欠矫组,采用重复测量资料分析方法比较两组患者3、5、7、9岁时远视性屈光不正的变化趋势.结果 足矫组患者,3岁屈光度(+5.45±2.22)D,5岁屈光度(+5.64±1.99)D,7岁屈光度(+5.48±2.05)D,9岁屈光度(+5.30±1.93)D.欠矫组患者,3岁屈光度(+3.98±2.14)D,5岁(+4.26±2.48)D,7岁(+3.97±2.43)D,9岁(+3.44±2.48)D.3～5岁,足矫组的远视屈光度增加+0.19 D,欠矫组增加+0.28 D(P ＜0.05);5～7岁,足矫组的远视屈光度下降+0.16 D,而欠矫组下降+0.29 D(P ＜0.05);7～9岁,足矫组的远视屈光度下降+0.18 D,欠矫组下降+0.53 D(P＜0.05).将两组患儿的研究始末的屈光度改变作比较,足矫组从3～9岁远视屈光度平均减少了+0.15 D,欠矫组则平均减小了+0.54 D.结论 配戴足度远视镜的3～9岁屈光性调节性内斜视儿童的正视化过程比远视欠矫的远视性屈光不正儿童慢.     

调节性内斜视儿童远视矫正后的散光变化

目的 观察调节性内斜视儿童远视矫正后的散光改变.方法 收集看远和看近内斜视10 PD以上、远视1.0 D以上、配戴足矫远视眼镜看远斜视度在10 PD以内的初诊病人;按初诊年龄分为≥2岁＜4岁组和≥4岁＜8岁组;根据睫状肌麻痹检影验光结果予以配戴足矫眼镜.每年再次验光,应用向量分解法,用90°～180°轴向的散光J180,及45°～135°轴向的散光J45作为散光统计指标.连续观察3年以上.结果 符合条件的调节性内斜视儿童共44名,平均初诊年龄(4.7±1.7)岁,观察(4.3±1.4)年.≥2岁＜4岁组儿童右眼的散光J180平均为(0.35 ±0.34)D,在配戴眼镜的第2年和第3年出现了分别为0.28 D、0.20 D的散光增加(P＜0.05),≥4岁＜8岁组右眼的散光J180,平均为(0.34±0.44)D,在戴镜后的第1年和第2年也分别增加了0.22 D和0.18 D(P ＜0.05),两组儿童在随后的2～3年下降到初诊水平并保持稳定;两组儿童的散光J45平均为(0.14±0.16)D、(-0.002±0.16)D,数值小且无明显变化.结论 调节性内斜视配戴远视足矫眼镜以后散光会出现少量的增加,之后有所降低,该变化与最初配戴眼镜的年龄无关.戴镜在一定时期内能影响儿童屈光的发育趋势.     

Optical correction of induced axial myopia in the tree shrew: implications for emmetropization.

PURPOSE: To determine whether an active emmetropization mechanism is involved in the recovery from axial myopia through the use of a mammalian model of refractive development. Specifically, we sought to establish whether the emmetropization mechanism is visually guided by the level of clarity of the image falling on the retina, or if recovery is driven by a mechanism sensitive to abnormal eye shape. METHODS: Young tree shrews had axial myopia induced by monocular deprivation (MD) of pattern vision and then the myopic eye was either: (1) accurately corrected with a negative lens or (2) had a zero-powered lens placed in front of it. Their emmetropization response was monitored, both through the use of ocular refractive and biometric measures, as well as through the assessment of scleral dry weight and glycosaminoglycan synthesis, as indicators of scleral metabolism. RESULTS: Corrective lenses prevented recovery from induced myopia (-6.8 +/- 0.7 D after 5 days MD vs. -6.6 +/- 0.6 D after 5 days of lens wear), whereas animals fitted with zero-powered lenses displayed near full recovery from the induced myopia (-6.6 +/- 0.6 D vs. -1.7 +/- 0.3 D). Significant reductions in scleral dry weight (-4.6 +/- 1.3%) and glycosaminoglycan synthesis (-28.6 +/- 7.3%) were found in the posterior sclera of animals wearing corrective lenses. Conversely, animals wearing zero-powered lenses displayed elevated levels of glycosaminoglycan synthesis (+62.3 +/- 11.1%) in conjunction with scleral dry weights that did not differ significantly between treated and fellow control eyes (-1.5 +/- 2.6%). CONCLUSIONS: Accurate correction of induced axial myopia prevents the refractive, biometric and scleral metabolic responses that are normally observed in tree shrew eyes recovering from induced myopia. These findings support the hypothesis that recovery is driven by an active emmetropization response dependent on the clarity of image falling on the retina and not by a mechanism that is sensitive to abnormal eye shape.     

Non-cycloplegic refractive screening can identify infants whose visual outcome at 4 years is improved by spectacle correction

The Second Cambridge Population Infant Vision Screening Programme using the VPR-1 videorefractor without cycloplegia was undertaken in order to identify those infants with refractive errors who were potentially amblyogenic or strabismogenic. Infants identified at eight months were entered into a control trial of treatment with partial spectacle correction and underwent a long-term follow-up that monitored a wide range of visual, visuoperceptual, visuocognitive, visuomotor, linguistic and social development. In the present paper, the authors report on the outcome measures of visual acuity and strabismus. Poor acuity was defined as a best-corrected acuity of 6/12 or worse on crowded letters or 6/9 or worse on single letters, at age 4 years. Acuity was measured in 79 infants who were significantly hyperopic and/or anisometropic at 11-12 months of age, 23 who showed hyperopia of +3D but less than +3.5D, 196 control subjects, 14 controls with refractive errors, and 126 others who showed an accommodative lag on screening but were not significantly hyperopic on first retinoscopy. There was a poorer acuity outcome in the untreated group of hyperopes compared to controls (p < 0.0001) and to the children who were compliant in spectacle wear (p < 0.001) or who were prescribed spectacles (p < 0.05). Children who were significantly hyperopic at eight months were also more likely to be strabismic by 5.5 years compared to the emmetropic control group (p < 0.001). However, the present study did not find a significant difference in the incidence of strabismus between corrected and uncorrected hyperopic infants. Children who were not refractively corrected for significant hyperopia were four times more likely to have poor acuity at 5.5 years than infants who wore their hyperopic correction, supporting the findings of the First Cambridge Population Infant Vision Screening Programme.     

One-year results of laser vision correction for low to moderate hyperopia

OBJECTIVE: To assess the efficacy and safety of hyperopic laser vision correction using a refined ablation architecture and the VISX STAR Excimer Laser. DESIGN: Prospective noncomparative case series. PARTICIPANTS: Fifty-two eyes with hyperopia from +1 to +6 diopters (D) spherical equivalent (SE) with or without cylinder < or =1.5 D based on cycloplegic refraction. Hyperopia was primary or caused by prior overcorrection of myopia. INTERVENTION: Hyperopic laser vision correction using a 9 mm/5 mm ablation profile and a pulse rate of 10 Hz. We prescribed ciprofloxacin and fluorometholone four times a day for 1 week. MAIN OUTCOME MEASURES: SE; uncorrected visual acuity (UCVA); predictability within +/- 0.5 D, +/- 1.0 D, and +/- 2.0 D of target refraction (emmetropia); loss of best-corrected visual acuity (BCVA); haze, and all complications at 1, 3, 6, and 12 months. RESULTS: We treated 52 eyes (mean preoperative SE; +3.03 D). Forty-one eyes (78.8%) had primary hyperopia. At 3, 6, and 12 months, 66%, 67%, and 79% of all eyes had refraction within +/-0.5 D of emmetropia. At these same intervals, 83%, 88%, and 79% were within +/-1.0 D of emmetropia. At 12 months, all eyes were within +/-2.0 D. At 3 months, 85.4% of eyes had UCVA of 20/40 or better, with 95.3% achieving 20/40 or better at 6 months. At 1 year, all eyes (n = 19) had gained from 1 to 8 Snellen lines of UCVA, with most (n = 16) gaining between 3 and 7 lines. At 12 months, all eyes maintained preoperative BCVA or gained 1 to 4 lines. There was some early, transient haze < or = grade 1.5. There were no corneal infiltrates, decentered ablations, or infections. CONCLUSIONS: These data suggest that the 9 mm/5 mm hyperopic ablation profile of the VISX STAR can produce accurate corrections without significant, progressive regression. Refractive stability was achieved 3 months after surgery. We did not observe any differences in outcomes between eyes treated for primary hyperopia and eyes treated for prior myopic overcorrections. We believe the quicker ablation time (10 Hz pulse rate) helped patients maintain fixation and reduced the risk of decentration. There was a high degree of satisfaction among all patients, especially those with presbyopia.