Subnormal visual acuity after compliant amblyopia therapy: residual/refractory amblyopia or co-existing pathology? - a retrospective analysis.

Purpose: To assess the prevalence of alternate etiology/co-existing pathology among patients with amblyopia, and to characterize factors contributing to over-diagnosis of amblyopia. Methods: We retrospectively reviewed records of children (from 1 January 2016 to 31 December 2019) who were initially diagnosed as "amblyopia" but later an alternate diagnosis for subnormal vision was established. Patients who had a best corrected visual acuity (BCVA) of ≤20/32 (0.2 logMAR) after compliant amblyopia therapy were divided into 2 groups: those with refractory amblyopia (BCVA improvement from baseline <1 logMAR line) and residual amblyopia (BCVA improvement from baseline >1 logMAR line). Data was collected for presence/absence of amblyogenic risk factors, history, ocular examination, and investigations leading to the final alternate diagnosis. We analyzed the factors that contributed to the initial over-diagnosis of amblyopia using the diagnostic error evaluation and research (DEER) taxonomy tool. Results: During the study period, 508 children with an initial diagnosis of amblyopia met the study criteria. Among these 508 children, 466 were diagnosed to have amblyopia alone, while 26 children (5.1%, median age: 7 years, 17 boys: 9 girls) were revised to have an alternate diagnosis/co-existing pathology. These 26 patients comprised of 2 groups: children referred to us as amblyopia but rediagnosed to have an alternate diagnosis; and a second subset, initially diagnosed by us to have amblyopia, but later found to have alternate diagnosis/co-existing pathology. Subclinical optic neuritis (50%, 13 children), and occult macular dystrophy (OMD) (38.4%, 10 children) were the most frequent alternative diagnoses. Children with ametropic amblyopia (8/26, 30.7%) were most frequently misdiagnosed. Risk factors that led to an initial diagnosis of amblyopia were: high refractive error and heterotropia in 7 patients each (26.9%), anisometropia in 12 (46.1%), and prior pediatric cataract surgery in 4(15.3%). No improvement in BCVA in 21/26 (80.7%) children led to suspicion of co-existing etiology. Other clues were optic disc pallor (11), subnormal color vision (7), history of parental consanguinity in 7, and preceding febrile illness/rhinitis in 1 child. The DEER taxonomy tool suggested that the most common reasons for diagnostic errors were over-emphasis on amblyopia. Conclusion: Our study suggests that 5% of children diagnosed with amblyopia might have co-existing/alternate etiology. Most common co-existing etiologies were subclinical optic neuropathy, and OMD. No improvement in BCVA, subtle history and examination findings prompted further workup. Not considering co-existing etiologies was the most common reason for an initial overdiagnosis of amblyopia.

Differentiating Occult Neuroretinitis and Non-Arteritic Anterior Ischaemic Optic Neuropathy: Clinical and Optical Coherence Tomography Characteristics.

We report clinical and optical coherence tomography (OCT) differences among patients with occult neuroretinitis and non-arteritic anterior ischaemic optic neuropathy (NAAION). We retrospectively reviewed records of patients with a final diagnosis of occult neuroretinitis and NAAION seen at our institute. Data were collected regarding patient demographics, clinical features, concomitant systemic risk factors, visual function, and optical coherence tomography (OCT) findings at presentation and subsequent follow-up. Fourteen and 16 patients were diagnosed to have occult neuroretinitis and NAAION, respectively. Patients with NAAION were slightly older (median age 49, inter-quartile range [IQR]: 45-54 years, versus 41, IQR: 31-50 years) than patients with neuroretinitis. Seventy-five per cent of patients with NAAION were male versus 43% with neuroretinitis (p = 0.07). Systemic risk factors were present in 87.5% of patients with NAAION versus 21.4% in patients with neuroretinitis (p = 0.001). At presentation, all patients presented with blurred vision, had similar visual function, and had optic disc oedema. In addition, none of the patients had evident retinitis lesions, but 10 (71%) showed evident retinitis lesion at follow-up. Neuroretinitis patients had more often vitreous cells (64% versus 6%, p = 0.001), and subretinal fluid (78.6% versus 37.5%, p = 0.03) than the patients with NAAION. In summary, NAAION patients tended to be slightly older, more often male, and had associated systemic diseases more often than those with neuroretinitis. Neuroretinitis patients more often had posterior vitreous cells and subretinal fluid on OCT. However, larger prospective studies are needed.