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.

Rare Thelazia californiensis infant ocular infestation.

Purpose: A rare case of Thelazia californiensis ocular infestation was diagnosed and treated in an 11-month-old patient. Observations: The patient presented with a visual acuity of 20/130 OU by Teller cards. Exam demonstrated a white, mobile worm in the inferomedial fornix of the right eye. The remainder of the exam was otherwise normal. The worm was removed under anesthesia and identified as Thelazia californiensis by the Division of Parasitic Diseases and Malaria, at the Centers for Disease Control and Prevention. Conclusions and importance: This case demonstrates a rare but important cause of follicular conjunctivitis and mobile foreign bodies, especially in patients with a supportive history of exposure to the intermediate and definitive hosts of Thelazia species.

Genotypic and Phenotypic Spectrum of Foveal Hypoplasia: A Multicenter Study.

PURPOSE: To characterize the genotypic and phenotypic spectrum of foveal hypoplasia (FH). DESIGN: Multicenter, observational study. PARTICIPANTS: A total of 907 patients with a confirmed molecular diagnosis of albinism, PAX6, SLC38A8, FRMD7, AHR, or achromatopsia from 12 centers in 9 countries (n = 523) or extracted from publicly available datasets from previously reported literature (n = 384). METHODS: Individuals with a confirmed molecular diagnosis and availability of foveal OCT scans were identified from 12 centers or from the literature between January 2011 and March 2021. A genetic diagnosis was confirmed by sequence analysis. Grading of FH was derived from OCT scans. MAIN OUTCOME MEASURES: Grade of FH, presence or absence of photoreceptor specialization (PRS+ vs. PRS-), molecular diagnosis, and visual acuity (VA). RESULTS: The most common genetic etiology for typical FH in our cohort was albinism (67.5%), followed by PAX6 (21.8%), SLC38A8 (6.8%), and FRMD7 (3.5%) variants. AHR variants were rare (0.4%). Atypical FH was seen in 67.4% of achromatopsia cases. Atypical FH in achromatopsia had significantly worse VA than typical FH (P < 0.0001). There was a significant difference in the spectrum of FH grades based on the molecular diagnosis (chi-square = 60.4, P < 0.0001). All SLC38A8 cases were PRS- (P = 0.003), whereas all FRMD7 cases were PRS+ (P < 0.0001). Analysis of albinism subtypes revealed a significant difference in the grade of FH (chi-square = 31.4, P < 0.0001) and VA (P = 0.0003) between oculocutaneous albinism (OCA) compared with ocular albinism (OA) and Hermansky-Pudlak syndrome (HPS). Ocular albinism and HPS demonstrated higher grades of FH and worse VA than OCA. There was a significant difference (P < 0.0001) in VA between FRMD7 variants compared with other diagnoses associated with FH. CONCLUSIONS: We characterized the phenotypic and genotypic spectrum of FH. Atypical FH is associated with a worse prognosis than all other forms of FH. In typical FH, our data suggest that arrested retinal development occurs earlier in SLC38A8, OA, HPS, and AHR variants and later in FRMD7 variants. The defined time period of foveal developmental arrest for OCA and PAX6 variants seems to demonstrate more variability. Our findings provide mechanistic insight into disorders associated with FH and have significant prognostic and diagnostic value.

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.

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.

Pediatric diabetic retinopathy telescreening.

PURPOSE: To describe the role of telemedicine screening for pediatric diabetic retinopathy (DR) and to identify risk factors for pediatric DR. METHODS: The medical records of a telemedicine program at a tertiary, academic medical center over 17 months were reviewed retrospectively. Patients visiting an academic pediatric endocrinology clinic who met guidelines underwent telescreening. Presence of pediatric DR and risk factors for retinopathy were evaluated. RESULTS: The fundus photographs of 852 patients 10-23 years of age were reviewed. Diabetic retinopathy was noted in 51 (6%). Patients with an abnormal screening photograph were compared to patients with diabetes who had normal screening photographs (n = 64). Older age, longer diabetes duration, type 1 diabetes, and higher average glycated hemoglobin (HbA1c) from the year prior to the photograph were associated with increased risk of retinopathy. Of these, longer duration (P = 0.003) and higher average A1c (P = 0.02) were significant after adjusting for sex, race, and age. CONCLUSIONS: Our telemedicine program found a higher percentage of diabetic retinopathy screening non-mydriatic photographs than prior studies found through standard ophthalmic examinations. In this relatively small sample size, longer duration of disease and higher average A1c were associated with increased risk of having diabetic retinopathy in our study.

Successfully Improving Visual Acuity in Keratitis-Ichthyosis-Deafness Syndrome Utilizing Gas-Permeable Lenses: A Case Report.

There is currently no well-defined guideline for treatment and management of patients with keratitis-ichthyosis-deafness (KID) syndrome, and most patients will face disabling vision loss due to corneal neovascularization and cicatrization. We offer this case as an example of how we can improve visual acuity (VA) and quality of life even in advanced cases of corneal neovascularization. We showcase the use of gas-permeable (GP) contact lenses to provide useful, functional VA in a patient with long-standing visual impairment secondary to corneal neovascularization and irregularity due to KID syndrome. The patient's VA improved from 20/200 both eyes (OU) to 20/40 OU with successful fitting of GP lenses, which additionally relieved the patient's otherwise intractable monocular diplopia.

Orbital cellulitis and intraconal abscess formation after strabismus surgery in an adult patient.

We report a 60-year-old woman who presented with orbital cellulitis, restricted ocular motility, proptosis, and visual acuity of counting fingers in her left eye 3 days after strabismus surgery. Although she initially responded well to antibiotic and anti-inflammatory therapy, visual acuity in the left eye again decreased on postoperative day 5. Radiographic imaging revealed an intraconal orbital abscess, and she underwent left lateral orbitotomy with abscess drainage, with continued antibiotics and a tapering dose of steroids. To our knowledge, this is the first case of orbital cellulitis and intraconal abscess after strabismus surgery in an adult.