Quantitative Foveal Structural Metrics as Predictors of Visual Acuity in Human Albinism

Purpose

To assess the degree to which quantitative foveal structural measurements account for variation in best-corrected visual acuity (BCVA) in human albinism.

Methods

BCVA was measured and spectral domain optical coherence tomography (SD-OCT) images were acquired for 74 individuals with albinism. Categorical foveal hypoplasia grades were assessed using the Leicester Grading System for Foveal Hypoplasia. Foveal anatomical specialization (foveal versus parafoveal value) was quantified for inner retinal layer (IRL) thickness, outer segment (OS) length, and outer nuclear layer (ONL) thickness. These metrics, participant sex, and age were used to build a multiple linear regression of BCVA. This combined linear model's predictive properties were compared to those of categorical foveal hypoplasia grading.

Results

The cohort included three participants with type 1a foveal hypoplasia, 23 participants with type 1b, 33 with type 2, ten with type 3, and five with type 4. BCVA ranged from 0.08 to 1.00 logMAR (mean ± SD: 0.53 ± 0.21). IRL ratio, OS ratio, and ONL ratio were measured in all participants and decreased with increasing severity of foveal hypoplasia. The best-fit combined linear model included all three quantitative metrics and participant age expressed as a binary variable (divided into 0-18 years and 19 years or older; adjusted R2 = 0.500). This model predicted BCVA more accurately than a categorical foveal hypoplasia model (adjusted R2 = 0.352).

Conclusions

A quantitative model of foveal specialization accounts for more variance in BCVA in albinism than categorical foveal hypoplasia grading. Other factors, such as optical aberrations and eye movements, may account for the remaining unexplained variance.

Examining Whether AOSLO-Based Foveal Cone Metrics in Achromatopsia and Albinism Are Representative of Foveal Cone Structure

Purpose

Adaptive optics scanning light ophthalmoscopy (AOSLO) imaging in patients with achromatopsia (ACHM) and albinism is not always successful. Here, we tested whether optical coherence tomography (OCT) measures of foveal structure differed between patients for whom AOSLO images were either quantifiable or unquantifiable.

Methods

The study included 166 subjects (84 with ACHM; 82 with albinism) with previously acquired OCT scans, AOSLO images, and best-corrected visual acuity (BCVA, if available). Foveal OCT scans were assessed for outer retinal structure, outer nuclear layer thickness, and hypoplasia. AOSLO images were graded as quantifiable if a peak cone density could be measured and/or usable if the location of peak density could be identified and the parafoveal mosaic was quantifiable.

Results

Forty-nine percent of subjects with ACHM and 57% of subjects with albinism had quantifiable AOSLO images. Older age and better BCVA were found in subjects with quantifiable AOSLO images for both ACHM (P = 0.0214 and P = 0.0276, respectively) and albinism (P = 0.0073 and P < 0.0004, respectively). There was a significant trend between ellipsoid zone appearance and ability to quantify AOSLO (P = 0.0028). In albinism, OCT metrics of cone structure did not differ between groups.

Conclusions

Previously reported AOSLO-based cone density measures in ACHM may not necessarily reflect the degree of remnant cone structure in these patients.

Translational Relevance

Until AOSLO is successful in all patients with ACHM and albinism, the possibility of the reported data from a particular cohort not being representative of the entire population remains an important issue to consider when interpreting results from AOSLO studies.

Does Early Glasses Wear Improve Visual Outcome in OCA1A?

Purpose: Oculocutaneous albinism type 1A (OCA1A), with lifelong absent melanin in skin, hair, and eyes, is the most severe type of albinism with greatest ametropia and poorest vision. We evaluated the relationship between age when spectacles were begun and visual outcome, in addition to status of refraction, in OCA1A. Methods: After IRB approval, a retrospective review of 70 consecutive charts of patients with OCA1A identified 24 fitting inclusion criterion of BCVA recorded at age 10-12 years. Exclusion criteria were those with other vision-threatening diagnoses and patients seen for a single visit. We recorded sex, age at beginning glasses, and refraction and BCVA at age 10-12 and most recent visit. Data were arbitrarily grouped by those initiating glasses at ≤ age 12 months and > age 12 months. Results: Regression analysis showed a larger degree of astigmatism was weakly associated with worse vision at age 10-12 years. A weakly positive relationship was found between poorer BCVA at last visit and older age at which glasses were initiated. All receiving glasses by age 1 and only half receiving glasses when older had improved visual acuity from age 10-12 years to last follow up. Conclusion: Additional study of a larger sample of this rare disorder is needed to determine if early glasses wear improves later BCVA.

Assessing Ganglion Cell Layer Topography in Human Albinism Using Optical Coherence Tomography

Purpose

To test whether ganglion cell layer (GCL) and inner plexiform layer (IPL) topography is altered in albinism.

Methods

Optical coherence tomography scans were analyzed in 30 participants with albinism and 25 control participants. Horizontal and vertical line scans were acquired at the fovea, then strip registered and averaged. The Duke Optical Coherence Tomography Retinal Analysis Program was used to automatically segment the combined GCL and IPL and total retinal thickness, followed by program-assisted manual segmentation of the boundary between the GCL and IPL. Layer thickness and area under the curve (AUC) were calculated within 2.5 mm of the fovea. Nasal-temporal and superior-inferior asymmetry were calculated as an AUC ratio in each quadrant.

Results

GCL and IPL topography varied between participants. The summed AUC in all quadrants was similar between groups for both the GCL (P = 0.84) and IPL (P = 0.08). Both groups showed nasal-temporal asymmetry in the GCL, but only participants with albinism had nasal-temporal asymmetry in the IPL. Nasal-temporal asymmetry was greater in albinism for both the GCL (P < 0.0001) and the IPL (P = 0.0006). The GCL usually comprised a greater percentage of the combined GCL and IPL in controls than in albinism.

Conclusions

The GCL and IPL have greater structural variability than previously reported. GCL and IPL topography are significantly altered in albinism, which suggests differences in the spatial distribution of retinal ganglion cells. This finding provides insight into foveal development and structure-function relationships in foveal hypoplasia.

An N-terminal heterozygous missense CASK mutation is associated with microcephaly and bilateral retinal dystrophy plus optic nerve atrophy

Heterozygous loss-of-function mutations in the X-linked gene CASK are associated with mental retardation and microcephaly with pontine and cerebellar hypoplasia (MICPCH) and ophthalmological disorders including optic nerve atrophy (ONA) and optic nerve hypoplasia (ONH). Recently, we have demonstrated that CASK^(+/-) mice display ONH with 100% penetrance but exhibit no change in retinal lamination or structure. It is not clear if CASK loss-of-function predominantly affects retinal ganglion cells, or if other retinal cells like photoreceptors are also involved. Here, we report a heterozygous missense mutation in the N-terminal calcium/calmodulin-dependent kinase (CaMK) domain of the CASK protein in which a highly conserved leucine is mutated to the cyclic amino acid proline. In silico analysis suggests that the mutation may produce destabilizing structural changes. Experimentally, we observe pronounced misfolding and insolubility of the CASK^L209P protein. Interestingly, the remaining soluble mutant protein fails to interact with Mint1, which specifically binds to CASK's CaMK domain, suggesting a mechanism for the phenotypes observed with the CASK^L209P mutation. In addition to microcephaly, cerebellar hypoplasia and delayed development, the subject with the L209P mutation also presented with bilateral retinal dystrophy and ONA. Electroretinography indicated that rod photoreceptors are the most prominently affected cells. Our data suggest that the CASK interactions mediated by the CaMK domain may play a crucial role in retinal function, and thus, in addition to ONH, individuals with mutations in the CASK gene may exhibit other retinal disorders, depending on the nature of mutation.

The Henle Fiber Layer in Albinism: Comparison to Normal and Relationship to Outer Nuclear Layer Thickness and Foveal Cone Density

Purpose

Directional optical coherence tomography (D-OCT) allows the visualization of the Henle fiber layer (HFL) in vivo. Here, we used D-OCT to characterize the HFL and outer nuclear layer (ONL) in albinism and examine the relationship between true foveal ONL and peak cone density.

Methods

Horizontal D-OCT B-scans were acquired, registered, and averaged for 12 subjects with oculocutaneous albinism and 26 control subjects. Averaged images were manually segmented to extract HFL and ONL thickness. Adaptive optics scanning light ophthalmoscopy was used to acquire images of the foveal cone mosaic in 10 subjects with albinism, from which peak cone density was assessed.

Results

Across the foveal region, the HFL topography was different between subjects with albinism and normal controls. In particular, foveal HFL thickness was thicker in albinism than in normal controls (P < 0.0001), whereas foveal ONL thickness was thinner in albinism than in normal controls (P < 0.0001). The total HFL and ONL thickness was not significantly different between albinism and controls (P = 0.3169). Foveal ONL thickness was positively correlated with peak cone density in subjects with albinism (r = 0.8061, P = 0.0072).

Conclusions

Foveal HFL and ONL topography are significantly altered in albinism relative to normal controls. Our data suggest that increased foveal cone packing drives the formation of Henle fibers, more so than the lateral displacement of inner retinal neurons (which is reduced in albinism). The ability to quantify foveal ONL and HFL may help further stratify grading schemes used to assess foveal hypoplasia.

Visual Development During the Second Decade of Life in Albinism

PURPOSE

To evaluate change in best corrected visual acuity (BCVA) during the second decade of life and the effects of albinism type and extraocular muscle surgery on BCVA in children with albinism.

METHODS

In this retrospective longitudinal study, 41 patients with albinism with clinic visits recording binocular BCVA at least once between the ages of 10 and 13 years (visit A) and again between the ages of 17 and 20 years (visit B) were included. Type of albinism, age at each visit, and interval eye muscle surgeries were recorded for each patient.

RESULTS

Forty (98%) patients showed BCVA improvement or stability between visits A and B. There was no significant effect of interval extraocular muscle surgery on BCVA. Those carrying either a clinically presumed or moleculary confirmed diagnosis of oculocutaneous albinism types 1B and 2 had the best visual outcomes, consistent with previous studies.

CONCLUSIONS

In the majority of patients with albinism, significant improvement in BCVA occurs during the second decade of life. Extraocular muscle surgery was not a significant factor in BCVA improvement in albinism. Overall, the assessments support the finding of improvement of visual acuity in children with albinism at earlier ages and provide new information beneficial in predicting visual outcomes in the second decade of life. [J Pediatr Ophthalmol Strabismus. 2018;55(4):254-259.].

Retinal dystrophy in two boys with Costello syndrome due to the HRAS p.Gly13Cys mutation

Features of Costello Syndrome, a systemic disorder caused by germline mutations in the proto-oncogene HRAS from the RAS/MAPK pathway, include failure-to-thrive, short stature, coarse facial features, cardiac defects including hypertrophic cardiomyopathy, intellectual disability, and predisposition to neoplasia. Two unrelated boys with Costello syndrome and an HRAS mutation (p.Gly13Cys) are presented with their ophthalmologic findings. Both had early symptoms of nystagmus, photophobia, and vision abnormalities. Fundus examination findings of retinal dystrophy were present at age 3 years. Both boys have abnormal electroretinograms with reduced or undetectable rod responses along with reduced cone responses consistent with rod-cone dystrophy. Our observations suggest that early ophthalmic examination and re-evaluations are indicated in children with Costello syndrome.

Outcomes of keratoplasty in the mucopolysaccharidoses: an international perspective

OBJECTIVE

To describe visual outcomes after penetrating keratoplasty and deep anterior lamellar keratoplasty in patients with mucopolysaccharidoses.

METHODS

This is a retrospective review of keratoplasty in consecutive patients from Brazil, England, Finland, Germany, Portugal, Sweden and the USA. All patients had corneal clouding due to mucopolysaccharidoses. Preoperative and postoperative visual outcome and ocular comorbidities were identified. Success was arbitrarily defined as any improvement in visual acuity or best-corrected visual acuity better than logarithm of the minimum angle of resolution 0.30 (20/40). Statistical analysis included only data from first operated eyes in the 16 patients who underwent bilateral keratoplasty.

RESULTS

Forty-eight eyes from 32 patients with mucopolysaccharidoses I, IV or VI are reported. Mean follow-up was 70 months (range: 5-186). Penetrating keratoplasty was performed in 45 eyes and deep anterior lamellar keratoplasty in 3 eyes. At last follow-up, a successful visual outcome for penetrating keratoplasty in first operated/only operated eyes was found in 63%. Rejection episodes occurred in 23% of grafts; however, a clear graft was recorded at last follow-up in 94%. Ocular pathway comorbidities were identified in 63% of eyes transplanted.

CONCLUSIONS

Clear corneal grafts can be obtained for patients with corneal clouding due to mucopolysaccharidosis with improvement in visual acuity in the majority.

Loss of MAFB Function in Humans and Mice Causes Duane Syndrome, Aberrant Extraocular Muscle Innervation, and Inner-Ear Defects

Duane retraction syndrome (DRS) is a congenital eye-movement disorder defined by limited outward gaze and retraction of the eye on attempted inward gaze. Here, we report on three heterozygous loss-of-function MAFB mutations causing DRS and a dominant-negative MAFB mutation causing DRS and deafness. Using genotype-phenotype correlations in humans and Mafb-knockout mice, we propose a threshold model for variable loss of MAFB function. Postmortem studies of DRS have reported abducens nerve hypoplasia and aberrant innervation of the lateral rectus muscle by the oculomotor nerve. Our studies in mice now confirm this human DRS pathology. Moreover, we demonstrate that selectively disrupting abducens nerve development is sufficient to cause secondary innervation of the lateral rectus muscle by aberrant oculomotor nerve branches, which form at developmental decision regions close to target extraocular muscles. Thus, we present evidence that the primary cause of DRS is failure of the abducens nerve to fully innervate the lateral rectus muscle in early development.

Concordance of visual and structural features between siblings with albinism

PURPOSE

To evaluate similarities and differences in visual function and ocular structure between siblings with albinism.

METHODS

The medical records of all siblings diagnosed with albinism were retrospectively reviewed. Comparisons were made using examination at oldest age for younger sibling and examination closest to that age for older siblings.

RESULTS

A total of 111 patients from 54 families were studied. Mean age was 12.9 years (range, 2 months to 44.2 years). Mean difference in ages between sibling pair examinations was 11.5 months (range, 0-87 months). Of 45 families, best-corrected visual acuity was equal in 9 (20%), within 1/2 octave in 9 (20%), >1/2 but <1 octave in 21 (47%), and ≥1 octave difference in 6 (13%). Of 27 families, stereoacuity was present in all siblings in 9 (33%), absent in 9 (33%), and present in only 1 sibling in 9 (33%). Of 54 families, grading of iris translucency was equal in 35 (65%) and different by 1 grade in 19 (35%). Of 54 families, foveal grading was equal in 39 (72%), different by 1 grade in 14 (26%), and different by ≥2 grades in 1 (2%). Macular melanin was present in all siblings in 16 of the 54 families (30%), absent in all siblings in 36 (67%), and present in only 1 sibling in 2 (4%) families.

CONCLUSIONS

The strong concordance of structural features is contrasted with discordance in visual function. Families of siblings with albinism should be counseled with due caution because visual function is often disparate despite similar structural findings.

Posterior staphyloma in oculocutaneous albinism: another possible cause of reduced visual acuity

Posterior staphyloma is typically associated with myopic degeneration and has not been recognized as a cause of reduced visual acuity in albinism. We report 3 cases of posterior staphyloma, each with oculocutaneous albinism (OCA) defined by phenotype and genotype. Two cases are biological sisters with OCA type 2; one was myopic and the other was hyperopic. The third case involves a man with OCA associated with Hermansky-Pudlak syndrome (HPS-5). Staphyloma may be another cause of reduced visual acuity in albinism, particularly with increasing age. It may occur in association with myopia or hyperopia.

Clinical Insights Into Foveal Morphology in Albinism

PURPOSE

A hallmark of albinism is foveal hypoplasia. However, literature suggests variable foveal development. This study evaluates the association between ocular phenotype and foveal morphology to demonstrate the broad structural and functional spectrum.

METHODS

Best-corrected visual acuity (BCVA), nystagmus, angle kappa, stereoacuity, iris transillumination, macular melanin presence, foveal avascular zone, and annular reflex were recorded in 14 patients with albinism. Spectral-domain optical coherence tomography provided macular images.

RESULTS

The clinical phenotype was broad, with BCVA varying from 20/20 to 20/100. Better BCVA was associated with a preserved foveal avascular zone, annular macular reflex, stereoacuity, and macular melanin. Imaging demonstrated a continuum of foveal development correlating with BCVA. Individuals with a rudimentary pit had normal inner and outer segment lengthening and better BCVA.

CONCLUSIONS

The spectrum of ocular structure and visual function in albinism is broad, suggesting a possible diagnosis of albinism in a patient with an even more normal clinical presentation.

Correlation of recognition visual acuity with posterior retinal structure in advanced retinopathy of prematurity

OBJECTIVE

To compare Early Treatment Diabetic Retinopathy Study visual acuity outcome with retinal structural outcome at the 6-year follow-up examination of infants randomized in the Early Treatment for Retinopathy of Prematurity study.

METHODS

We compared the results in 606 eyes of subjects in whom both functional (visual acuity) and retinal structural assessments were obtained at age 6 years. Visual acuity assessments were performed by masked testers,and retinal examinations were performed by certified ophthalmologists.

MAIN OUTCOME MEASURES

Visual acuity and retinal structure at age 6 years.

RESULTS

Concordant outcomes occurred in 462 eyes(76.2%): 402 eyes had favorable functional and structural outcomes and 60 eyes had unfavorable functional and structural outcomes. Discordant outcomes occurred in 92 eyes (15.2%): 86 eyes had unfavorable functional and favorable structural outcomes and 6 eyes had favorable functional and unfavorable structural outcomes.Of the 86 eyes with unfavorable functional and favorable structural outcomes, 43 had optic atrophy (23 eyes) and/or retinal abnormalities that were less severe than those considered to be unfavorable (32 eyes). In 52 eyes (8.6%), retinal structure could not be assessed or the visual acuity was untestable.

CONCLUSION

Posterior pole appearance correlates well with visual acuity in 6-year-old infants with a history of advanced retinopathy of prematurity.

Relationship between foveal cone specialization and pit morphology in albinism

PURPOSE

Albinism is associated with disrupted foveal development, though intersubject variability is becoming appreciated. We sought to quantify this variability, and examine the relationship between foveal cone specialization and pit morphology in patients with a clinical diagnosis of albinism.

METHODS

We recruited 32 subjects with a clinical diagnosis of albinism. DNA was obtained from 25 subjects, and known albinism genes were analyzed for mutations. Relative inner and outer segment (IS and OS) lengthening (fovea-to-perifovea ratio) was determined from manually segmented spectral domain-optical coherence tomography (SD-OCT) B-scans. Foveal pit morphology was quantified for eight subjects from macular SD-OCT volumes. Ten subjects underwent imaging with adaptive optics scanning light ophthalmoscopy (AOSLO), and cone density was measured.

RESULTS

We found mutations in 22 of 25 subjects, including five novel mutations. All subjects lacked complete excavation of inner retinal layers at the fovea, though four subjects had foveal pits with normal diameter and/or volume. Peak cone density and OS lengthening were variable and overlapped with that observed in normal controls. A fifth hyper-reflective band was observed in the outer retina on SD-OCT in the majority of the subjects with albinism.

CONCLUSIONS

Foveal cone specialization and pit morphology vary greatly in albinism. Normal cone packing was observed in the absence of a foveal pit, suggesting a pit is not required for packing to occur. The degree to which retinal anatomy correlates with genotype or visual function remains unclear, and future examination of larger patient groups will provide important insight on this issue.

Does levodopa improve vision in albinism? Results of a randomized, controlled clinical trial

BACKGROUND

Dopamine is an intermediate product in the biosynthesis of melanin pigment, which is absent or reduced in albinism. Animal research has shown that supplying a precursor to dopamine, levodopa, may improve visual acuity in albinism by enhancing neural networks. This study examines the safety and effectiveness of levodopa on best-corrected visual acuity in human subjects with albinism.

DESIGN

Prospective, randomized, placebo-controlled, double-masked clinical trial conducted at the University of Minnesota.

PARTICIPANTS

Forty-five subjects with albinism.

METHODS

Subjects with albinism were randomly assigned to one of three treatment arms: levodopa 0.76 mg/kg with 25% carbidopa, levodopa 0.51 mg/kg with 25% carbidopa, or placebo and followed for 20 weeks, with best-corrected visual acuity measured at enrollment, and at weeks 5, 10, 15, and 20 after enrollment. Side-effects were recorded with a symptom survey. Blood was drawn for genotyping.

MAIN OUTCOME MEASURES

Side-effects and best-corrected visual acuity 20 weeks after enrolment.

RESULTS

All subjects had at least one mutation found in a gene known to cause albinism. Mean age was 14.5 years (range: 3.5 to 57.8 years). Follow up was 100% and compliance was good. Minor side-effects were reported; there were no serious adverse events. There was no statistically significant improvement in best-corrected visual acuity after 20 weeks with either dose of levodopa.

CONCLUSIONS

Levodopa, in the doses used in this trial and for the time course of administration, did not improve visual acuity in subjects with albinism.

A comparison of treatment approaches for bilateral congenital nasolacrimal duct obstruction

PURPOSE

To compare the clinical outcomes of two treatment approaches for bilateral nasolacrimal duct obstruction (NLDO) in infancy.

DESIGN

Multicenter, randomized clinical trial.

METHODS

We studied 57 infants between the ages of 6 and <10 months who had bilateral NLDO. Participants were randomized to receive either (1) immediate office-based probing within two weeks (n = 31) or (2) 6 months of observation and nonsurgical management followed by surgical facility-based probing for unresolved cases (n = 26). Treatment success was defined as the absence of clinical signs of NLDO (epiphora, increased tear lake, mucous discharge) in both eyes on masked examination at 18 months of age.

RESULTS

In the observation and deferred facility probing group, resolution without surgery occurred by 6 months after randomization in both eyes for 14 participants (56%), in one eye for 5 (20%), and in neither eye for 6 (24%). Eight participants in the observation and deferred facility probing group underwent facility probing (one of whom later had a second facility probing). Four participants in the immediate office probing group later underwent an additional procedure in a surgical facility. In the immediate office probing group, treatment success at 18 months of age occurred in both eyes for 19 of 29 (66%) participants and in one eye for 3 (10%); in the observation and deferred facility probing group, treatment success occurred in both eyes for 19 of 25 (76%) participants and in one eye for 3 (12%) (difference in success = -10%; 95% CI = -35% to 14%).

CONCLUSIONS

Both the immediate office probing approach and the observation and deferred facility probing approach are successful and reasonable treatment options for infants with bilateral NLDO.

The unique association of iris heterochromia with Hermansky-Pudlak syndrome

Melanin biosynthesis is reduced in oculocutaneous albinism, an autosomal recessive disorder. Hermansky-Pudlak syndrome is associated with oculocutaneous albinism but also has systemic complications. The ocular and systemic phenotypes vary, depending, in part, on the genetic mutations. This report presents a case of a patient with Hermansky-Pudlak syndrome and the unique association of iris heterochromia.

Hermansky-Pudlak syndrome (HPS5) in a nonagenarian

Hermansky-Pudlak syndrome (HPS) is an autosomal-recessive disorder clinically characterized by oculocutaneous albinism, bleeding diatheses, and lysosomal accumulation of ceroid lipofuscin, which in some cases may cause granulomatous colitis and pulmonary fibrosis. Any of these complications could result in a shortened life span for patients with HPS. We report a 92-year-old man with HPS 5 who, to our knowledge, is the oldest patient with HPS documented in the literature. This report highlights the importance of typing HPS to counsel patients regarding disease prognosis.

Clinical characteristics of children with severe visual impairment but favorable retinal structural outcomes from the Early Treatment for Retinopathy of Prematurity (ETROP) study

PURPOSE

To describe visual function and associated characteristics at the 6-year examination in children enrolled in the Early Treatment for Retinopathy of Prematurity Study who had unfavorable visual outcomes despite favorable structural outcomes in one or both eyes.

METHODS

The clinical examination records of children completing the 6-year follow-up examination were retrospectively reviewed. Eligible subjects were those with visual acuity of ≤20/200 in each eye (where recordable) and a normal fundus or straightening of the temporal retinal vessels with or without macular ectopia in at least one eye. Data regarding visual function, retinal structure, presence of nystagmus, optic atrophy, optic disk cupping, seizures/shunts, and Functional Independence Measure for Children (ie, WeeFIM: pediatric functional independence measure) developmental test scores were reviewed.

RESULTS

Of 342 participants who completed the 6-year examination, 39 (11%) met inclusion criteria. Of these, 29 (74%) had normal retinal structure, 18 (46%) had optic atrophy, and 3 (8%) had increased cupping of the optic disk in at least one eye. Latent and/or manifest nystagmus occurred in 30 children (77%). The presence of nystagmus was not related to the presence of optic atrophy. Of the 39 children, 28 (72%) had a below-normal WeeFIM score.

CONCLUSIONS

In 25 participants (7%) completing the 6-year examination, cortical visual impairment was considered the primary cause of visual loss. The remainder likely had components of both anterior and posterior visual pathway disease. Clinical synthesis of ocular anatomy and visual and neurologic function is required to determine the etiology of poor vision in these children.

Clinical overview and treatment options for non-skeletal manifestations of mucopolysaccharidosis type IVA

Mucopolysaccharidosis type IVA (MPS IVA) or Morquio syndrome is a multisystem disorder caused by galactosamine-6-sulfatase deficiency. Skeletal manifestations, including short stature, skeletal dysplasia, cervical instability, and joint destruction, are known to be associated with this condition. Due to the severity of these skeletal manifestations, the non-skeletal manifestations are frequently overlooked despite their significant contribution to disease progression and impact on quality of life. This review provides detailed information regarding the non-skeletal manifestations and suggests long-term assessment guidelines. The visual, auditory, digestive, cardiovascular, and respiratory systems are addressed and overall quality of life as measured by endurance and other functional abilities is discussed. Impairments such as corneal clouding, astigmatism, glaucoma, hearing loss, hernias, hepatomegaly, dental abnormalities, cardiac valve thickening and regurgitation, obstructive sleep apnea, tracheomalacia, restrictive and obstructive respiratory compromise, and muscular weakness are discussed. Increased awareness of these non-skeletal features is needed to improve patient care.

Correlation of recognition visual acuity with posterior retinal structure in advanced retinopathy of prematurity

OBJECTIVE To compare Early Treatment Diabetic Retinopathy Study visual acuity outcome with retinal structural outcome at the 6-year follow-up examination of infants randomized in the Early Treatment for Retinopathy of Prematurity study. METHODS We compared the results in 606 eyes of subjects in whom both functional (visual acuity) and retinal structural assessments were obtained at age 6 years. Visual acuity assessments were performed by masked testers, and retinal examinations were performed by certified ophthalmologists. MAIN OUTCOME MEASURES Visual acuity and retinal structure at age 6 years. RESULTS Concordant outcomes occurred in 462 eyes (76.2%): 402 eyes had favorable functional and structural outcomes and 60 eyes had unfavorable functional and structural outcomes. Discordant outcomes occurred in 92 eyes (15.2%): 86 eyes had unfavorable functional and favorable structural outcomes and 6 eyes had favorable functional and unfavorable structural outcomes. Of the 86 eyes with unfavorable functional and favorable structural outcomes, 43 had optic atrophy (23 eyes) and/or retinal abnormalities that were less severe than those considered to be unfavorable (32 eyes). In 52 eyes (8.6%), retinal structure could not be assessed or the visual acuity was untestable. CONCLUSION Posterior pole appearance correlates well with visual acuity in 6-year-old infants with a history of advanced retinopathy of prematurity. APPLICATION TO CLINICAL PRACTICE When the retinal structure is normal but visual acuity is poor in infants with a history of severe retinopathy of prematurity, other diagnoses such as optic atrophy and cortical visual impairment could at least partially account for the discrepancy. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00027222.

Clinical guidelines for diagnosing and managing ocular manifestations in children with mucopolysaccharidosis

The mucopolysaccharidoses (MPS) are a group of rare lysosomal storage disorders characterized by the accumulation of glycosaminoglycans in several tissues and organs. This accumulation results in an array of clinical manifestations and premature death in severe cases. Ocular problems are very common in children with MPS and may involve the cornea, sclera, trabecular meshwork, retina, optic nerve and also the posterior visual pathways. The aims of this study are to give an overview of ocular problems in MPS and to provide clinical guidelines for paediatric ophthalmologists for early diagnosis and management of ocular manifestations in children with MPS. Diagnostic problems may arise in children with severe corneal clouding, hampering visualization of the fundus. Intraocular pressures may be falsely high, even leading to suspicion and unnecessary pressure-lowering treatment. Simple interventions such as the use of prescription glasses or photochromatic glasses can considerably improve quality of life in children with MPS.

Reading skills in children and adults with albinism: the role of visual impairment

PURPOSE

To evaluate whether visual impairment in albinism contributes significantly to the acquisition of normal reading skills.

METHODS

The authors administered standardized reading tests to 41 children and 18 adults with albinism. The Young Children's Achievement Test was used for children between 4 and 6 years old and the Woodcock-Johnson III was used for children 7 years and older and adults. Parents of children and adult subjects also completed a questionnaire to document developmental, academic, and/or work experiences. The Spearman test was used to evaluate the relationship between binocular best-corrected visual acuity (BCVA) and reading test results.

RESULTS

Standardized reading tests in both children and adults with albinism showed a normal distribution of scores. BCVA did not appear to play a significant role in the development of normal reading ability in these individuals who were visually impaired except for a mild correlation of decreased reading fluency on the Woodcock-Johnson III with decreased BCVA (r = 0.287, P = .046). Many young children with albinism had superior reading skills despite having a BCVA of 20/200 or worse (legal blindness).

CONCLUSION

This study of cognitively normal children and adults with albinism demonstrates that impaired vision during childhood does not by itself significantly impede a child's ability to acquire normal reading skills. However, the lower reading fluency that occurs in the more visually impaired individuals suggests they would benefit, both in the school system and workplace, with an accommodation involving more time to complete reading tasks.

Use of a Driving Simulator to Assess Performance under Adverse Weather Conditions in Adults with Albinism

Participants with albinism have reduced vision and nystagmus with reduced foveation times. This prospective study evaluated driving in 12 participants with albinism and 12 matched controls. Participants drove a vehicle simulator through a virtual rural course in sunny and foggy conditions. Under sunny conditions, participants with albinism showed a narrower preferred minimum safety boundary during car-following tasks than did controls, but there was no difference under foggy conditions. Their driving did not differ significantly from that of controls when approaching a stop sign or when choosing gap size between oncoming vehicles when crossing an intersection. However, when compared to control drivers, participants with albinism had a decreased minimum safety boundary for car-following that should be included in counseling regarding driving safety.

Change in visual acuity in albinism in the early school years

PURPOSE

To determine whether binocular best-corrected visual acuity (B-BCVA) improves in the early school years in patients with albinism and whether this is related to type of albinism, ocular pigment, or appearance of the macula.

METHODS

Patients with albinism seen between 5.5 and 9 years (Visit A) and 9.5 and 14 years of age (Visit B), with visits separated by at least 2.5 years, were included. Type of albinism, B-BCVA, glasses wear, iris pigment and macular transparency grade, and presence or absence of an annular reflex and melanin in the macula were recorded.

RESULTS

Mean B-BCVA was 20/84 at Visit A and 20/61 at Visit B (P < .001). B-BCVA improved in 80%. Improvement in B-BCVA and glasses wear, iris grade, macular grade, macular melanin, and annular reflex were weakly correlated. However, a moderate correlation was found between measured B-BCVA and iris grade at Visit A (r = 0.485, P < .001) and Visit B (r = 0.467, P < .001), and the presence of macular melanin at Visit A (r = 0.436, P < .001) and Visit B (r = 0.482, P < .001).

CONCLUSIONS

B-BCVA often improves in albinism in the early school years and this observation should be included in counseling. The etiology is unknown but may be related to change in nystagmus, use of precise null point, developmental maturation, and/or some of the ocular characteristics evaluated in this study.

Axenfeld-Rieger syndrome: new perspectives

Axenfeld-Rieger syndrome is a genetic disease affecting multiple organ systems. In the eye, this condition manifests with varying degrees of anterior segment dysgenesis and carries a high risk of glaucoma. Other associated systemic issues include cardiovascular outflow tract malformations, craniofacial abnormalities and pituitary abnormalities, which can result in severe endocrinological sequelae. Recent advances in molecular genetics have identified two major genes, PITX2 and FOXC1, demonstrating a wide spectrum of mutations, which aids in the molecular diagnosis of the disease, although evidence exists to implicate other loci in this condition. The management of individuals affected by Axenfeld-Rieger syndrome requires a multidisciplinary approach and would include dedicated surveillance and management of glaucoma, sensorineural hearing loss, and cardiac, endocrinological, craniofacial and orthopaedic abnormalities.

Ocular manifestations as key features for diagnosing mucopolysaccharidoses

Diagnosis of mucopolysaccharidosis (MPS) requires awareness of the multisystem disease manifestations and their diverse presentation in terms of time of onset and severity. Many patients with MPS remain undiagnosed for years and progressively develop irreversible pathologies, which ultimately lead to premature death. To foster timely treatment and ensure a better outcome, it is of utmost importance to recognize and evaluate the typical ocular features that present fairly early in the course of the disease in many children with MPS. These include corneal clouding, ocular hypertension/glaucoma, retinal degeneration, optic disc swelling and optic nerve atrophy. Other associations include pseudo-exophthalmos, amblyopia, strabismus and large refractive errors requiring spectacle correction. While some ocular manifestations require specialized equipment for detecting abnormalities, light sensitivity, pseudo-exophthalmos and strabismus are often apparent on a routine physical examination. In addition, patients may be symptomatic from vision impairment, photosensitivity, night blindness and visual field constriction. Combined with the skeletal/joint complications and other manifestations, these ocular features are key in the differential diagnosis of children with joint abnormalities. Rheumatologists should have a high index of suspicion for MPS to facilitate early diagnosis. Referral to a geneticist, a metabolic specialist or physician who specializes in MPS can confirm the diagnosis and provide disease management. Consultation with an ophthalmologist who has expertise in MPS is also needed for thorough examination of the eyes and regular follow-up care.

Grating visual acuity results in the early treatment for retinopathy of prematurity study

OBJECTIVE

To compare grating (resolution) visual acuity at 6 years of age in eyes that received early treatment (ET) for high-risk prethreshold retinopathy of prematurity (ROP) with that in eyes that underwent conventional management (CM).

METHODS

In a randomized clinical trial, infants with bilateral, high-risk prethreshold ROP (n = 317) had one eye undergo ET and the other eye undergo CM, with treatment only if ROP progressed to threshold severity. For asymmetric cases (n = 84), the high-risk prethreshold eye was randomized to ET or CM.

MAIN OUTCOME MEASURE

Grating visual acuity measured at 6 years of age by masked testers using Teller acuity cards.

RESULTS

Monocular grating acuity results were obtained from 317 of 370 surviving children (85.6%). Analysis of grating acuity results for all study participants with high-risk prethreshold ROP showed no statistically significant overall benefit of ET (18.1% vs 22.8% unfavorable outcomes; P = .08). When the 6-year grating acuity results were analyzed according to a clinical algorithm (high-risk types 1 and 2 prethreshold ROP), a benefit was seen in type 1 eyes (16.4% vs 25.2%; P = .004) undergoing ET, but not in type 2 eyes (21.3% vs 15.9%; P = .29).

CONCLUSION

Early treatment of eyes with type 1 ROP improves grating acuity outcomes, but ET for eyes with type 2 ROP does not. APPLICATION TO CLINICAL MEDICINE: Type 1 eyes should be treated early; however, based on acuity results at 6 years of age, type 2 eyes should be cautiously monitored for progression to type 1 ROP. Trial Registration clinicaltrials.gov Identifier: NCT00027222.

Outcome of penetrating keratoplasty for mucopolysaccharidoses

OBJECTIVE

To describe the outcome of penetrating keratoplasty (PK) for corneal opacification in the setting of systemic mucopolysaccharidoses (MPS).

METHODS

A consecutive case series and literature review.

RESULTS

Eight eyes from 5 patients with MPS (MPS I, MPS IV, and MPS VI) and a history of PK met inclusion criteria for our case series at the University of Minnesota Medical Center. The mean age at the time of PK was 40.5 years (range, 11.7-65.3 years). Mean follow-up time after the PK was 4.9 years (range, 1-11 years). Mean (SD) visual acuity before PK was 0.90 (0.38) logMAR. The mean (SD) visual acuity at the last visit for all 8 eyes was 0.32 (0.16) logMAR. Visual acuity improved in 7 of 8 eyes (P = .002). Although early rejection led to repeat PK in 1 eye, no recurrent opacity consistent with MPS was noted in any of the corneal grafts. In a literature review, we found 23 reports documenting 40 initial and 3 repeat cases of PK in the setting of MPS. Of these, 31 initial and 2 repeat corneal grafts were reportedly clear during follow-up, ranging from 0.25 to 13 years.

CONCLUSIONS

Penetrating keratoplasty is often a beneficial intervention in appropriate patients with corneal clouding due to MPS. Improvement in vision can be obtained with stable, clear corneal grafts in this population.

Reading acuity in albinism: evaluation with MNREAD charts

INTRODUCTION

The MNREAD reading acuity (RA) charts use continuous-text reading to measure (1) RA, ie, the smallest size of print that the patient can resolve; (2) maximum reading speed (MRS); and (3) critical print size (CPS), ie, the smallest print that the patient can read with maximum speed. This project used the MNREAD charts to evaluate reading performance in children and adults with albinism to determine the smallest print size recommended to facilitate effortless reading.

METHODS

A total of 63 subjects with albinism were administered the MNREAD test to determine the critical print size for effortless reading. The subjects read continuous, high-contrast text print until they could no longer discern the words. The MRS and CPS were determined with the MNREAD protocol. Presence or absence of nystagmus and strabismus was recorded. Distance visual acuity was measured with ETDRS charts.

RESULTS

The sample included 25 male and 38 female subjects with a median age of 16 years. Median MRS was 150 words per minute. The mean CPS was 0.84 logMAR, notably larger than the mean RA of 0.53 logMAR.

CONCLUSIONS

The MNREAD acuity charts can be used to determine functional reading ability and critical print size for effortless reading in individuals with albinism. The amount of enlargement in print size can be used in educational and vocational recommendations to facilitate reading.

Diagnosis and management of ophthalmological features in patients with mucopolysaccharidosis

Ocular pathology is common in patients with mucopolysaccharidosis (MPS), a hereditary lysosomal storage disorder, where the eye as well as other tissues accumulate excessive amounts of glycosaminoglycans. Despite genetic and phenotypic heterogeneity within and between different types of MPS, the disease symptoms and clinical signs often manifest during the first 6 months of life with increasing head size, recurrent infections, umbilical hernia, growth retardation and skeletal problems. Typical ocular features include corneal clouding, ocular hypertension/glaucoma, retinal degeneration and optic nerve atrophy. Visual deterioration and sensitivity to light may substantially reduce the quality of life in MPS patients, particularly when left untreated. As an early intervention, haematopoietic stem cell transplantation and/or enzyme replacement therapy are likely to improve patients' symptoms and survival, as well as visual outcome. Thus, it is of utmost importance to ensure proper detection and accurate diagnosis of MPS at an early age. It is of fundamental value to increase awareness and knowledge among ophthalmologists of the ocular problems affecting MPS patients and to highlight potential diagnostic pitfalls and difficulties in patient care. This review provides insight into the prevalence and severity of ocular features in patients with MPS and gives guidance for early diagnosis and follow-up of MPS patients. MPS poses therapeutic challenges in ocular management, which places ophthalmologists next to paediatricians at the forefront of interventions to prevent long-term sequelae of this rare but serious disease.

Periocular granuloma annulare in four children

Subcutaneous granuloma annulare is a skin condition that occurs on the lower extremities, hands, and scalp of healthy children. It rarely occurs in the periocular area, and when it does, the annular pattern is often absent. Histopathology is diagnostic and shows palisading histiocytes around areas of necrobiosis. Although benign in nature, the lesions tend to multiply, grow in size, and often recur. They usually resolve spontaneously and do not require treatment. Four cases of periocular subcutaneous granuloma annulare, from four different geographical areas, were identified through on-line postings on the worldwide mailing list of the Organization for Pediatric Ophthalmology and Strabismus (http://lists.ucsd.edu/mailman/listinfo/ped-ophth-1). These 4 patients are reported here, and a brief review of the literature is presented.

Outcome of angle surgery in children with aphakic glaucoma

PURPOSE

To investigate the outcome of trabeculotomy and/or goniotomy for pediatric aphakic glaucoma.

METHODS

Retrospective chart review of consecutive children who had congenital cataract surgery between 1990 and 2006 and required goniotomy and/or trabeculotomy for aphakic glaucoma. Treatment success was defined as postoperative intraocular pressure of <or=24 mm Hg despite topical medication use, avoidance of trabeculectomy or shunt placement, and no visually significant complications in the follow-up period. Exclusion criteria included a diagnosis of anterior segment dysgenesis, microcornea, and glaucoma at the time of cataract surgery, and follow-up less than 1 year.

RESULTS

A total of 14 eyes of 11 patients met inclusion criteria, with a mean follow-up of 4.7 years. Of theses, 2 eyes had goniotomy alone, 3 eyes had goniotomy followed by trabeculotomy, and 9 eyes had trabeculotomy alone. Mean IOP before angle surgery was 35 +/- 10 mm Hg. Mean IOP at the last recorded visit was 22 +/- 4 mm Hg (p = 0.0005). Treatment success was observed in 8 of the 14 eyes (57.1%), with a mean number of angle procedures of 1.4 per eye: 6 eyes (42.8%) were successful after a single angle surgery, each involving an initial trabeculotomy; 3 eyes (21.4%) underwent subsequent shunt placement after initial goniotomy at 6 months, 1.3 years, and 5.5 years after the last angle surgery.

CONCLUSIONS

When intraocular surgery is indicated to control IOP in pediatric aphakic glaucoma, trabeculotomy and/or goniotomy can be successful in the majority of eyes and may decrease the need for filtering and shunting procedures.

Arrested development: high-resolution imaging of foveal morphology in albinism

Albinism, an inherited disorder of melanin biosynthesis, disrupts normal retinal development, with foveal hypoplasia as one of the more commonly associated ocular phenotypes. However the cellular integrity of the fovea in albinism is not well understood - there likely exist important anatomical differences that underlie phenotypic variability within the disease and that also may affect responsiveness to therapeutic intervention. Here, using spectral-domain optical coherence tomography (SD-OCT) and adaptive optics (AO) retinal imaging, we obtained high-resolution images of the foveal region in six individuals with albinism. We provide a quantitative analysis of cone density and outer segment elongation demonstrating that foveal cone specialization is variable in albinism. In addition, our data reveal a continuum of foveal pit morphology, roughly aligning with schematics of normal foveal development based on post-mortem analyses. Different albinism subtypes, genetic mutations, and constitutional pigment background likely play a role in determining the degree of foveal maturation.

Evaluation of vision-specific quality-of-life in albinism

INTRODUCTION

Human albinism is a genetic condition associated with visual impairment that affects many aspects of daily life. Office measurements of visual acuity do not necessarily reflect daily visual function and health status. This study used the National Eye Institute Visual Function Questionnaire (NEI-VFQ) to determine the effect of albinism-associated ophthalmopathy on quality of life (QOL).

METHODS

We administered the NEI-VFQ, which consists of 25 questions about QOL (VFQ-25) and 14 questions about well-being (VFQ-39), to 44 consenting participants with albinism older than the age of 18 years.

RESULTS

Nineteen male and 25 female subjects completed the study. Median age was 30.5 years (range, 18-79 years). Mean best-corrected visual acuity was 20/83 (range, 20/20 to 20/320). Forty-eight percent reported that they were currently able to drive with their condition. Participants perceived midscale problems with their general vision (median subscale score 60.0). Visual acuity correlated moderately with overall NEI-VFQ composite scores (r(s) = 0.40, p = 0.01 for VFQ-25 and r(s) = 0.36, p = 0.02 for VFQ-39). Most notable impairment was recorded for distance acuity, vision-specific mental health, and vision-specific role difficulties (VFQ-39 median subscale scores 66.7, 70.0, and 75.0, respectively). Differences by sex were insignificant. Greater ceiling effects were noted for the VFQ-25 than for the VFQ-39.

CONCLUSIONS

The NEI-VFQ-39 is a method to evaluate self-reported effects of vision-related QOL in albinism and may be used as a baseline for evaluating outcomes in interventional studies in these patients.

The prevalence of attention-deficit/hyperactivity disorder among persons with albinism

Attention-deficit/hyperactivity disorder (ADHD) is a common diagnosis in children and adults. Human albinism is an uncommon genetic condition associated with visual impairment that may affect behavior. To determine if there is a relationship between albinism and ADHD, the prevalence of ADHD was examined among 78 children (age range, 4-18 years) and among 44 adults (age range, 19-79 years) with ocular or oculocutaneous albinism. ADHD was diagnosed in the pediatric population using a combination of Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) criteria, Conners' Parent Rating Scale, and physician observation. Adults were diagnosed using the Utah criteria for ADHD as confirmed by physician history and interview. Seventeen children (22.7% [17 of 75]) (3 children with existing diagnoses of pervasive developmental disorder were identified but were not included in the data analysis) and 3 adults (6.8%) met the criteria for ADHD. The combined hyperactivity and impulsivity subtype of ADHD was most common, accounting for 50% of the diagnoses. Binocular best-corrected visual acuity and genetic type of albinism were not found to correlate with a diagnosis of ADHD. The prevalence of ADHD among children and adults with albinism is more frequent than that reported among the general population and is not related to binocular best-corrected visual acuity.

Sectoral iris heterochromia and retinal pigment variation in 13q-syndrome

Chromosome 13q deletion syndrome is characterized by growth retardation, cognitive delays, and organ and musculoskeletal deformities. Typical ocular associations include retinoblastoma, microphthalmia, and colobomas. We report a case of bilateral iris heterochromia and retinal pigment abnormalities in a child with 13q-syndrome.

Spectrum of foveal development in albinism detected with optical coherence tomography

BACKGROUND

Optical coherence tomography (OCT) has shown the absence of a foveal depression in an individual with oculocutaneous albinism, type 1 (OCA1) and best-corrected visual acuity (BCVA) of 20/400. However, the presence of an annular light reflex in the macula has been noted with indirect ophthalmoscopy in other patients with albinism who have better vision. We studied macular architecture in albinism with OCT when binocular BCVA was > or = 20/60 and compared this to detection of foveal development with binocular indirect ophthalmoscopy.

METHODS

Eleven patients with albinism and BCVA > or = 20/60 were recruited for OCT. Average central macular thickness was recorded. Presence of an oval annular reflex was determined with binocular indirect ophthalmoscopy.

RESULTS

Mean binocular BCVA was 20/39 (range: 20/20 to 20/50). Twelve eyes had a rudimentary annular reflex detected with ophthalmoscopy. OCT was reliable in 20 of 22 eyes. A foveal depression was identified with OCT in four eyes. Mean macular thickness for these four eyes was 233 microm (+/- 22.5 microm). We found a weak inverse correlation between BCVA (logMAR) and thickness (r = -0.21).

CONCLUSIONS

OCT shows the spectrum of foveal development in albinism, from complete absence of development to a central depression corresponding to a rudimentary annular reflex detected with ophthalmoscopy. The reduced rate of detection of foveal development with OCT compared with ophthalmoscopy is likely related to poor fixation in patients with nystagmus.

Strabismus and amblyopia in bilateral Peters anomaly

BACKGROUND

Peters anomaly is a rare form of anterior segment dysgenesis in which abnormal cleavage of the anterior chamber occurs at the end of the third week of gestation. We examined the prevalence of strabismus and amblyopia and analyzed predictive factors for their development, as well as the visual outcome and associated anomalies in patients with bilateral Peters anomaly.

METHODS

Using a retrospective review, we identified 25 consecutive patients with bilateral Peters anomaly who were observed between August 1995 and February 2005. Ocular structural and systemic anomalies, amblyopia therapy, visual acuity, and binocular alignment at last visit were recorded. Fisher's exact test was used to identify any association between defined predictive factors and the development of strabismus.

RESULTS

Mean follow-up time was 5.1 year (range, 0.5-21 years). Median age at presentation was 2.5 months (range, 1 day to 13 years). Penetrating keratoplasties were performed on 34 eyes in 20 patients. Final best-corrected visual acuity ranged from 20/25 to no light perception. Thirteen of 18 patients with recorded motility (72%) developed strabismus: esotropia (n = 7), exotropia (n = 5), and variable (n = 1); one also had dissociated vertical deviation. Patients with equal vision were either orthophoric (n = 4) or had intermittent esotropia (n = 1), whereas strabismus occurred in 100% of patients whose vision was asymmetric by more than 1.5 octaves. Asymmetric vision was the only statistically significant predictive factor for the development of strabismus (P = 0.002). Amblyopia treatment resulted in improved vision in 3 of 5 patients.

CONCLUSION

Strabismus occurs frequently in bilateral Peters anomaly. Asymmetric vision, (because of ocular structural anomalies) postoperative complications, and amblyopia may predispose to strabismus. Despite ocular structural limitations, amblyopia therapy is recommended in the aggressive rehabilitation of these eyes.

Correlation of grating acuity with letter recognition acuity in children with albinism

PURPOSE

This study was undertaken to determine whether grating acuity in early childhood can be used as a predictor of letter recognition acuity in patients with albinism.

METHODS

In this retrospective study, we compared the binocular grating acuities of children with albinism (30 at age 1, 29 at age 2, and 19 at age 3) to their letter recognition acuity at age 4-6 years.

RESULTS

Mean binocular grating acuity was 2.0, 1.9, and 1.5 octaves below age matched norms at ages 1, 2, and 3 years, respectively (P<0.001 at all ages). Mean grating acuity at ages 1, 2, and 3 correlated moderately (r=0.458, 0.502, and 0.471, respectively; all with P<0.05) with mean binocular letter recognition acuity of the same children at ages 4-6. A subgroup analysis of 9 patients followed longitudinally showed strong correlation of binocular grating acuity at ages 1 and 2 with letter acuity (r=0.745, P=0.021; r=0.930, P<0.001, respectively) and moderate correlation at age 3 (r=0.685, P=0.042). In the larger group and the longitudinal subgroup, mean binocular grating acuity at ages 1 and 2 was worse than mean binocular letter recognition acuity at age 4-6 (paired-samples t-test, P<0.001). Mean binocular grating acuity at age 3 in both groups was not significantly different than mean binocular letter recognition acuity at age 4-6 (paired-samples t-test, P=0.790, 0.215, respectively).

CONCLUSION

Parents should be informed that vision measured as grating acuity at age 3 provides an estimate of future letter recognition acuity in children with albinism.