Novel membrane frizzled‐related protein gene mutation as cause of posterior microphthalmia resulting in high hyperopia with macular folds

Purpose: We present a genetic and clinical analysis of two sisters, 3 and 4 years of age, with nanophthalmos and macular folds. Methods: Ophthalmological examination, general paediatric examination and molecular genetic analysis of the MFRP gene were performed in both affected siblings. Results: Clinical analysis showed high hyperopia (+11 D and +12 D), short axial lengths (15 mm) and the presence of macular folds and optic nerve head drusen. Autofluorescence of the retina was generally normal with subtle macular abnormalities. Sequence analysis showed compound heterozygosity for severe MFRP mutations in both sisters: a previously reported p.Asn167fs (c.498dupC) and a novel stop codon mutation p.Gln91X (c.271C>T). Conclusion: These are the youngest nanophthalmos patients in the literature identified with severe loss of MFRP function, showing already the known structural abnormalities for this disease. Adult patients affected by homozygous or compound heterozygous MFRP mutations generally show signs of retinal dystrophy, with ERG disturbances and RPE abnormalities on autofluorescence imaging. ERG examination could not be performed in these children, but extensive RPE abnormalities were not seen at this young age.     

Emmetropisation and the aetiology of refractive errors

The distribution of human refractive errors displays features that are not commonly seen in other biological variables. Compared with the more typical Gaussian distribution, adult refraction within a population typically has a negative skew and increased kurtosis (ie is leptokurtotic). This distribution arises from two apparently conflicting tendencies, first, the existence of a mechanism to control eye growth during infancy so as to bring refraction towards emmetropia/low hyperopia (ie emmetropisation) and second, the tendency of many human populations to develop myopia during later childhood and into adulthood. The distribution of refraction therefore changes significantly with age. Analysis of the processes involved in shaping refractive development allows for the creation of a life course model of refractive development. Monte Carlo simulations based on such a model can recreate the variation of refractive distributions seen from birth to adulthood and the impact of increasing myopia prevalence on refractive error distributions in Asia.     

Genetic susceptibility and mechanisms for refractive error

Refractive errors, myopia and hyperopia, are the most common causes of visual impairment worldwide. Recent advances in genetics have been utilized to identify a wealth of genetic loci believed to contain susceptibility genes for refractive error (RE). The current genetic evidence confirms that RE is influenced by both common and rare variants with a significant environmental component. These studies argue that only by combining genetic and environmental knowledge with in vivo measurements of biological states will it be possible to understand the underlying biology of RE that will lead to novel therapeutic targets and accurate genetic predictions.     

远视性屈光不正图像筛查结果分析

目的采用瞬息图像筛查分析仪分析远视性屈光图像,以期提高转诊儿童中弱视诊断的准确率。方法于2009年1月至2010年11月应用瞬息图像筛查分析仪对眼科门诊6个月～4岁的29例(51眼)儿童进行致弱视因子筛查,应用二元线性相关分析研究远视性屈光不正图像中新月影/瞳孔的值与屈光度数之间的关系,并分析图像中内斜视的表现。结果线性相关分析得出新月影/瞳孔的值与屈光度数的回归方程为:屈光度数=-0.197+9.095×新月影/瞳孔。通过图片检查出11例内斜视儿童,其图像表现为多种形式。结论在瞳孔统一的情况下,通过新月影的大小可以推断出屈光度数,结合儿童的年龄可以提高转诊儿童中弱视的诊断率。     

Associations of early age‐related macular degeneration with ocular and general parameters. The central India eyes and medical study

Purpose: To assess associations between age‐related macular degeneration (AMD) and ocular and general parameters. Methods: The Central India Eye and Medical Study, a population‐based study performed in rural Central India, included 4711 subjects (aged 30+ years) out of 5885 eligible subjects (response rate: 80.1%). Fundus photographs were assessed using the Wisconsin Age‐Related Maculopathy Grading system. Results: Fundus photographs were available for 4542 (96.4%) subjects. Early AMD was present in 215/4542 subjects (4.7 ± 0.3%), and late AMD was detected in 8/4542 (0.2 ± 0.03%) subjects. After adjustment for age, prevalence of AMD was significantly associated with hyperopic refractive error (p = 0.001), shorter axial length (p = 0.01), and higher corneal refractive power (p = 0.02). Each dioptre increase in hyperopic refraction or each millimetre decrease in axial length was associated with a 15% [odds ratio (OR):1.15; 95% confidence interval (CI): 1.06, 1.24] and 19% (OR: 0.81; 95%CI: 0.69, 0.95) increased probability of early AMD, respectively. AMD was not significantly associated with blood pressure, serum concentration of cholesterol, glycosylated haemoglobin Hb1Ac, high‐density lipoproteins and postprandial glucose, gender, level of education, any parameter of smoking, alcohol consumption, psychiatric depression or of daily activities, anterior chamber depth, lens thickness, intraocular pressure, size of the optic disc, neuroretinal rim and parapapillary atrophy, nor amount of nuclear cataract and status after cataract surgery. If the statistical analysis was adjusted for age and refractive error, age‐related macular degeneration was marginally significantly associated with a low intake of fruits (p = 0.06). Conclusions: Hyperopia (and short axial length) besides age was the single most important associated factor for AMD in adult Indians.     

Ocular higher-order aberrations and mesopic pupil size in individuals screened for refractive surgery

AIM: To study the distribution of ocular higher-order aberrations(HOAs) and mesopic pupil size in individuals screened for refractive surgery. METHODS: Ocular HOAs and mesopic pupil size were studied in 2 458 eyes of 1 240 patients with myopia, myopic astigmatism and compound myopic astigmatism and 215 eyes of 110 patients with hyperopia, hyperopic astigmatism and compound hyperopic astigmatism using the Zywave aberrometer (Busch& Lomb). All patients had correctable refractive errors without a history of refractive surgery or underlying diseases. Root-mean-square values of HOAs, total spherical aberration, total coma and mesopic pupil size were analyzed. Ocular HOAs were measured across a ≥ 6.0 mm pupil, and pupil size measurements were performed under the mesopic condition. RESULTS: The mean values of HOAs, total spherical aberration and total coma in the myopic group were 0.369μm, ±0.233, 0.133± 0.112μm and 0.330±0.188μm, respectively. In the hyperopic group the mean values of HOAs, total spherical aberration and total coma were 0.418μm ±0.214, 0.202±0.209μm and 0.343±0.201μm, respectively. Hyperopes showed greater total HOAs (P<0.01) and total spherical aberration (P<0.01) compared to myopes. In age-matched analysis, only the amount of total spherical aberration was higher in the hyperopic group (P=0.05). Mesopic pupil size in the myopic group was larger (P≤0.05). CONCLUSION: The results suggested that significant levels of HOAs were found in both groups which are important for planning refractive surgeries on Iranians. There were significantly higher levels of total spherical aberration in hyperopes compared to myopes. Mesopic pupil size was larger in myopic group.     

钬激光角膜热成形术的疗效分析

目的:评价钬激光角膜热成形术(LTK)治疗轻度远视的疗效、安全性和并发症。方法:我们的研究对年龄>45岁的患者12例18只轻度远视眼行Ho:YAG激光LTK术治疗,能量密度65J/cm~2,平均随访2a。结果:患者年龄45～65(平均55.25±10.12)岁,术前屈光度+0.50～+2.25(平均+1.30±0.58)D,术前裸眼视力0.44±0.23,术后屈光度得以全部矫正,术后1mo,没有屈光回退,术后3mo,4眼屈光回退+0.25D。术后6mo,剩余屈光度在±0.50D和±1.00D以内的百分率分别为83%,89%,已矫屈光度和预矫屈光度符合率较好。之后存在屈光回退趋势,2a后屈光回退减缓。最佳视力出现在术后2wk内,以后裸眼视力开始回退。术前裸眼视力>1.0者为0,术后1mo,裸眼视力均较术前有非常显著的提高。术后3mo,裸眼视力达1.0者14眼(78%)。术后2a,裸眼视力达1.0者10眼(56%)。结论:Ho:YAG激光LTK术对轻度远视有效。临床观察证实此手术方法简单、安全,见效快以及并发症少等优点,为治疗轻度远视的手术方方法之一,但尚需长期观察其屈光稳定性。     

LASIK治疗远视眼的初步结果分析

目的　为了评价激光原位角膜磨镶术(excimerlaserinsitukeratomileusis,LASIK)治疗远视眼的有效性、预测性和安全性。方法　对19例原发性远视眼患者( 1.00～ 8.50D),采用LASIK进行治疗,术后平均随访6mo(3～9mo)。结果　至术后6mo时,平均残余屈光度为 0.22D±0.79D,84.2%的患者屈光度在±1.0D以内,89.5%的患者裸眼视力达到0.5以上。结论　LASIK可有效地治疗 1.00～ 6.00D的远视眼且具有较好的预测性和安全性。对手术技术和激光治疗程序的不断改进将有助于进一步提高手术的预测性和稳定性。     

准分子激光原位角膜磨镶术治疗远视的临床观察

目的:观察和评价用准分子激光原位角膜磨镶术(laserin situ keratomileusis,LASIK)治疗远视的安全性、有效性和稳定性。方法:应用德国鹰视蓝调酷眼准分子激光治疗仪机远视治疗程序治疗远视及合并散光的患者18例33眼。术后观察视力、屈光度及阅读舒适性改变,所有患者均随访6~12mo。结果:至术后3mo时,平均残余屈光度为+0.22±0.79D,91%的患者屈光度在±1.0D以内,97%患者裸眼视力达到0.5以上。术后所有患者感觉阅读舒适,阅读时间超过1h无头痛、眼胀等不适。结论:LASIK手术治疗远视是一种安全有效且稳定性好的方法。     

Screening for abnormal levels of hyperopia in children: a non-cycloplegic method with a hand held refractor

AIMS—High hyperopia constitutes the majority of refractive errors in large scale visual screening at preschool ages. The authors aimed to assess the validity of the Retinomax hand held refractor to detect high hyperopia in a refractive screening performed without cycloplegia and carried out on children aged 9-36 months. They considered +1.5 D of manifest hyperopia to be the threshold value and abnormal absolute hyperopia to be above +3.5 D.
METHODS—Of the 897 children screened without cycloplegia, 220 were refracted with cycloplegia. The validity of several thresholds of manifest hyperopia was estimated by receiver operating characteristic (ROC) curves using cycloplegic measures as a reference. The reproducibility of Retinomax measurements was assessed. Normal and quick mode measurements were compared using the Wilcoxon test.
RESULTS—The manifest threshold of +1.5 D offered the best combination of sensitivity (70.2%), specificity (94.6%), positive predictive value (78.6%), and negative predictive value (91.9%) to disclose abnormal absolute hyperopia. A good agreement was obtained between the various measurements using Retinomax on the same subject. In the results of this survey, there is no evidence that accommodation is minimised in the normal mode of measurement compared with the quick mode.
CONCLUSION—The Retinomax hand held infrared autorefractor is a suitable instrument to diagnose abnormal hyperopia (manifest hyperopia >+1.5 D) in non-cycloplegic refractive screening at preschool ages. It is suggested as the quick mode of measurement as it is more feasible in children (success rate 98.5%).

Keywords: non-cycloplegic refractive screening; hyperopia; hand held infrared automated refractor; Retinomax