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Glaucoma suspect shows subtle retinal nerve fiber layer thinning
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A 33-year-old female was seen at a community screening and referred for a glaucoma work-up due to the combined risk factors of positive family history for glaucoma and the observation of a large cup-to-disc ratio.
She was employed as a nurse. Her ocular history was noncontributory, with the exception of refractive correction and mention of amblyopia. A review of systems including cardiovascular, ears, nose, mouth, throat, respiratory, gastrointestinal, genitourinary, musculoskeletal, integumentary, neurological, psychiatric and endocrine were noncontributory. The patient took no medications and had no reported allergies. Her reported family medical history was positive for diabetes among unknown ancestors.
Visual acuity was correctable to 20/20 in each eye with minimal refractive correction (plano, +0.25 OD, OS). Neither tropia nor extraocular motility restriction was observed. IOP was 16 mm Hg OD and 18 mm Hg OS measured by Goldmann at 9:30 a.m. Pachymetry was 567 microns OD and 562 microns OS. The anterior segment of each eye was unremarkable, and the anterior chamber angles were open, showing ciliary body band 360 degrees in each eye.
Dilated fundus examination was performed, and the results of the posterior pole evaluation are shown. In addition, optical coherence tomography imaging of the optic nerve head (ONH) and retinal nerve fiber layer (RNFL) as well as the macular ganglion cell complex (GCC) were obtained. Finally, visual field testing was performed.
Stereoscopic observation of the optic nerve heads shows distinct disc margins in each eye. The optic nerve area is small in both the right and left eyes. There appears to be a subtle superior temporal RNFL defect in the right eye but no evidence of a corresponding notch. The left rim tissue and RNFL appear to be intact. No optic disc hemorrhages were observed. Interestingly, the patient had archived photographs from 5 years earlier.
Optic disc cube scans. There is evidence of superior temporal thinning of the RNFL in the
right eye and RNFL thinning temporally, superior nasally and superiorly in the left eye.
Images: Semes LP
Ganglion cell analysis. Note the distinct pattern of thinning in the left superior quadrant in
each macula.
Left optic nerve head. Note the distinct disc margins, intact rim tissue, concordance with the
ISNT rule and intact temporal RNFL. The macular appearance is a photographic artifact. The
size of the optic disc appears larger due to some parapapillary temporal stretching. Note the
cilioretinal artery at about 2 o’clock.
Visual field of the left (left) and right (right) eyes. The 24-2 SITA Standard strategy showed
minimal fixation losses in each eye but were otherwise reliable. The pattern of depressions is
clearly concentrated in the inferior nasal and temporal field regions in the right and left eyes,
respectively.
Right optic nerve head. Note the distinct disc margins, intact rim tissue, concordance with the
ISNT (inferior-superior-nasal-temporal) rule and subtle superior temporal RNFL thinning. The
macular appearance is a photographic artifact.
Evaluation of the RNFL/ONH OCT outputs show good signal strength in each eye. The segmentation algorithms are good, also indicating good data. Average RNFL thickness is suspicious at 84 microns OD and 85 microns OS. There is some asymmetry between the optic nerve areas and the superior temporal RNFL thinning with some sporadic areas of RNFL thinning in the left eye and to a lesser extent in the right eye. This is reflected in the RNFL profile, as well. Note some superior nasal RNFL thinning in the left eye. The cup volume is larger in the left eye. The macular GCC scans show corresponding right superior quadrant thinning in each eye.
Posterior pole photographs of the right and left eyes from 5 years earlier. Note the similarity to the current presentation in the other images.
Our interpretation of the data suggested little evidence to support a diagnosis of glaucoma. The superior quadrant involvement of the RNFL and GCC with corresponding visual field depressions suggested involvement of higher visual pathways. This evidence is supported by the visual field data. These results prompted us to entertain the possibility of a parietal lobe lesion.
One rare, extreme example of parietal-lobe lesions that affects males is known as the Bannayan-Riley-Ruvalcaba’s syndrome. Affected individuals generally show macrocephaly and often exhibit delays in development or autism. This case met none of the qualifications for this syndrome, and we pursued further diagnostic analyses. After consultation that included MR imaging of the brain, it was interpreted to be a mild, likely congenital parietal lobe lesion that is nonprogressive. We will continue to monitor the patient on an annual basis to confirm the stable nature of the condition.