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Ashutosh Richhariya, Sanjay Kumar, PremNandhini Satgunam, Ruchi Priya; Subclinical features of a Microtropic patient uncovered by using Adaptive optics scanning laser ophthalmoscope (AOSLO).. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4611.
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© ARVO (1962-2015); The Authors (2016-present)
In the last three centuries, the name and definition of Microtropia (MT) has undergone numerous changes due to the variability in clinical presentations. MT is a disease considered as a result of refractive, neural, or motor anomalies. The patients were believed to have a normal retina to an extent that even the central scotoma reported in some cases was considered as an perimetry artifact. This study extends our understanding of MT by uncovering retinal structural changes in patients and highlights the need for a careful follow up. This study also highlights the use of AOSLO as primary diagnostic tool, and that where all other modalities have failed to record structural changes.
Three patients diagnosed with MT, and ten control subjects were enrolled for the study. The findings of unexplained reduced visual acuity and a positive 4 prism base out test were used to diagnose MT.The images of fovea were obtained using AOSLO having 790nm reflectance mode imaging in a confocal mode. The photoreceptor cones count of patients were compared with the average count of age-matched control subjects.
The cones in images of the 10 normal subjects were counted and mean value was used to benchmark cone density in normal Asian population. Out of three, in two patients diagnosed with MT had a consistent patch (~50 micron hyporeflective region) where the photoreceptor cells were lost. The count of photoreceptor in the region was low as compared to control subjects. Thus the patient cell count in those areas was lower than normal but remained stable between consecutive follow up visits. The third patient had a normal retina structure and the loss of visual acuity remains unexplained.
Using AOSLO, we report the sub-clinical retinal structural deficit in some MT patients. This may challenge the previous dogma where it was assumed that the problem is in visual cortex but not within the structure of retina. This report demonstrates the potential use of AOSLO as a diagnosis tool for further sub differentiation of MT.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
Symptomatic Eye (OD) of the patient (a) On first Visit (b)On second visit
Photoreceptor Cell count in normal vs Microtropic patient on 1st and 2nd visit
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