Tapetal-like reflex in X-linked RPGR-associated retinopathy
Srikanta Kumar Padhy1, Brijesh Takkar2, Sujoy Mukherjee1
1Anant Bajaj Retina Institute, LV Prasad Eye Institute, MTC Campus, Bhubaneswar, India.
Purpose:
To investigate the clinical, imaging, electrophysiological, and genetic characteristics of male patients with RPGR-associated retinopathy exhibiting tapetal-like reflex (TLR) versus those without (non-TLR).
Methods:
This retrospective observational study included 9 Indian males from 7 unrelated families with genetically confirmed pathogenic RPGR variants. Patients were divided into TLR (n=6) and non-TLR (n=3) groups based on fundus appearance. Multimodal imaging (fundus photography, fundus autofluorescence [FAF], optical coherence tomography [OCT]) and full-field electroretinography (ERG) were analyzed. Molecular genetic testing was performed to identify RPGR variants.
Results:
The TLR group showed a characteristic golden, scintillating sheen with radial streaks on fundus exam. Median age of onset was 35 years with worse best-corrected visual acuity (BCVA) (0.66 LogMAR) and higher myopia (median -5.50 D) compared to the non-TLR group (23 years, 0.26 LogMAR, -1.00 D). FAF in the TLR group revealed central confluent or patchy macular atrophy surrounded by hyper-autofluorescence, whereas the non-TLR group exhibited widespread mid-peripheral degeneration and bull's eye maculopathy. OCT showed complete outer retinal atrophy (cRORA) in most TLR eyes and incomplete atrophy (iRORA) with preserved ellipsoid zone in the youngest patient. Non-TLR eyes demonstrated milder retinal atrophy with limited ellipsoid zone preservation. Full-field ERG demonstrated preserved scotopic but extinguished photopic responses in TLR eyes, while non-TLR eyes had extinguished photopic and severely reduced scotopic responses. All variants were hemizygous RPGR mutations in exon 15, predominantly frameshift or stop-gain mutations.
Conclusions:
Tapetal-like reflex in male RPGR-associated retinopathy correlates with a cone-rod dystrophy-like phenotype featuring later onset, severe central atrophy, and predominant photopic dysfunction. In contrast, absence of TLR associates with rod-cone dystrophy-like features. Recognition of TLR may aid clinical classification, early diagnosis, and prognosis in RPGR-related retinal disease.
