Microperimetry in a case of occult macular dystrophy

RP1L1 and inherited photoreceptor disease: A review

Retinitis pigmentosa 1-like 1 (RP1L1) is a component of the photoreceptor cilium. Pathogenic variants in RP1L1 lead to photoreceptor disease, suggesting an important role for RP1L1 in photoreceptor biology, though its exact function is unknown. To date, RP1L1 variants have been associated with occult macular dystrophy (a cone degeneration) and retinitis pigmentosa (a rod disease). Here, we summarize reported RP1L1-associated photoreceptor conditions and disease-causing RP1L1 variants. We also discuss novel associations between RP1L1 and additional photoreceptor conditions-besides occult macular dystrophy and retinitis pigmentosa-and fit RP1L1 into the broader scope of photoreceptor disease. RP1L1 appears to have a complex relationship with other photoreceptor proteins and may modify disease phenotype. Ultimately, further exploration of the relationship between RP1L1, other cilium components, and their impact on photoreceptor health is needed.

Fixation behavior in macular dystrophy assessed by microperimetry

Purpose

To investigate the fixation behavior in macular dystrophy using microperimetry.

Methods

This retrospective study included patients with macular dystrophy and unilateral macular pucker. Macular dystrophic eyes were compared based on fixation within or outside of the atrophic region. The normal fellow eyes in patients with unilateral macular pucker formed the control group. Clinical and demographic characteristics of age, sex, best-corrected visual acuity, spherical equivalent, and fixation behavior (which included foveal mean sensitivity (MS), fixation MS, MS improvement, stability, centrality, and eccentric distance of fixation) were analyzed. A total of 58 patients were recruited, comprising 29 eyes of 29 patients in the macular dystrophy group and 29 eyes of 29 patients in the control group.

Results

Compared to the control group, patients with macular dystrophy had significantly poorer visual acuity, foveal MS, fixation MS, stability, and centrality, and more eccentric preferred retinal locations (PRLs). In macular dystrophy, the PRLs were most common on the superior side (48.3%). Compared to fixation in the atrophic region, PRLs out of the atrophic lesion gained more MS (7.41 vs. 0.89 dB, p = 0.001), although with less stable fixation (10.0 vs. 47.4%, p = 0.044). By multivariate linear regression, eccentric distance was found to be significantly associated with MS improvement (p = 0.023).

Conclusions

The commonest location of PRLs in macular dystrophy is anatomically superior to the lesion. The dystrophic eye can gain better sensitivity by using PRLs outside the atrophic area.

Occult Macular Dystrophy

Occult macular dystrophy is an inherited macular dystrophy characterized by a progressive decline of bilateral visual acuity with normal fundus appearance, fluorescein angiogram and full-field electroretinogram. This case report presents a 20-year-old female patient with bilateral progressive decline of visual acuity for six years. Her visual acuity was 3-4/10 in both eyes. Anterior segment and fundus examination, fluorescein angiogram and full-field electroretinogram were normal. She could read all Ishihara pseudoisochromatic plates. Fundus autofluorescence imaging was normal. There was a mild central hyporeflectance on fundus infrared reflectance imaging in both eyes. Reduced foveal thickness and alterations of the photoreceptor inner and outer segment junction were observed by optical coherence tomography in both eyes. Central scotoma was also found by microperimetry and reduced central response was revealed by multifocal electroretinogram in both eyes. These findings are consistent with the clinical characteristics of occult macular dystrophy.