The edition · Ophthalmology
Three-quarters of healthy eyes have a red patch on the ganglion cell map
In 194 normal eyes, false positives on OCT deviation maps were the rule rather than the exception, and they got worse as the eye got longer. Also: myopic globes remodel in shapes that predict damage better than axial length, a reference map that fixes ROP zoning, and a very large NSAID cohort that proves less than it looks.
The edition in brief
A retrospective cross-sectional study of 194 healthy eyes examined false positives on spectral-domain OCT deviation maps. Colour-coded abnormal areas appeared in 76.1% of ganglion cell analyses and 62.2% of retinal nerve fibre layer maps. For ganglion cell maps the rate rose with axial length: 45.2% below 23 mm, 51.2% at 23 to 25 mm, and 87.5% at 25 mm or more (p<0.001). Hyperopic eyes most often showed a small doughnut pattern (67.9%); highly myopic eyes showed diffuse thinning and inferior crescent patterns (both 38.1%). Axial length independently predicted false positives (OR 1.09-2.64), as did older age (OR 1.04-1.06). A 15-year MRI substudy of the Zhongshan High Myopia Cohort rescanned 30 participants (60 eyes) with spherical equivalent -6.00 D or worse. Eyes were classified as quiescent (35.0%), proportional expansion (20.0%), focal emergence (23.3%), focal progression (10.0%) or shape transition (11.7%); no deformed eye reverted. Proportional expansion dominated under age 20 (83.3%), focal progression or shape transition at 40 and over (54.2%). At similar axial elongation, focal deformation carried more myopic macular degeneration progression (91.7% vs 58.8%, P=.02), posterior staphyloma (91.7% vs 17.6%, P<.001) and myopic traction maculopathy (58.3% vs 11.8%, P=.003). A crossover reader study in which four ophthalmologists assessed 85 retinopathy of prematurity examinations found an anatomically derived quantitative zone reference map raised reader-reference agreement from kappa 0.58 to 0.92 and interobserver agreement from 0.47 to 0.86; for Zone III versus non-Zone III, from 0.40 to 0.88. A propensity-matched TriNetX cohort of 634,794 pairs reported lower age-related macular degeneration risk among people prescribed NSAIDs (HR 0.58, 95% CI 0.56-0.59), with the strongest effect at six months (HR 0.31).
The shape a myopic eye takes matters more than how long it gets
At the same amount of axial elongation, highly myopic eyes that deformed focally had far more macular degeneration, staphyloma and traction maculopathy than those that expanded proportionally — shape, not just length, predicts damage.
A reference map turns ROP zoning from judgement into measurement
A quantitative zone reference map raised interobserver agreement for ROP zoning from kappa 0.47 to 0.86, and Zone III classification from 0.40 to 0.88 — the unaided baseline is the finding that should worry any screening programme.
A very large study finding that NSAIDs prevent macular degeneration, and why to distrust it
A 1.27 million-patient database found NSAID users had lower macular degeneration risk (HR 0.58), but the effect was strongest at six months and faded with time — the signature of ascertainment bias, not of prevention.
Check the axial length before you believe the deviation map
A red sector on an OCT deviation map is a comparison against a normative database of average-length eyes — check the axial length, open the B-scan, and require a second line of evidence before it changes management.
False positives on OCT deviation maps are the norm, not the exception
Three-quarters of healthy eyes showed a false positive on the ganglion cell deviation map, rising to 87.5% in eyes 25 mm or longer — in a long eye, an abnormal map is more likely to be the database than the disease.
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