Pigment dispersion syndrome diagnosed after photorefractive
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Laser vision correction enjoys vast demand as a cosmetic procedure as well as a means of complying with occupational vision standards.It is an elective procedure and most patients seeking refractive surgery have high expectations from the procedure. The onus of patient selection lies in the surgeon and necessitates meticulous examination to ensure a successful surgery and a happy patient. The majority of patients presenting for refractive surgeries are young myopes. However, pigment dispersion syndrome (PDS) is another uncommon condition that is prevalent in a demographically similar population. PDS is characterized by the presence of pigments on the corneal endothelium, an increase of pigmentation of the trabecular meshwork, and mid-periphery transillumination defects of the iris.

Pigment deposition on the trabecular meshwork can lead to increased intraocular pressure (IOP) eventually leading to glaucomatous optic neuropathy known as pigmentary glaucoma (PG), a form of secondary open-angle glaucoma. PDS typically occurs in patients between 20 and 40 years of age and a majority of them are myopes; the more myopic the eye, the more likely it is to develop PDS. It is not uncommon for these patients to seek opinions for refractive surgery. Since PDS can progress to a potentially sight-threatening condition (PG), it is essential for a refractive surgeon to be aware of its clinical features to ensure that this condition is diagnosed and monitored appropriately.

A 23-year-old Indian male presented with complaints of recurrent episodes of mild pain and blurring of vision OU after performing strenuous physical exercise for the past 2 months. These episodes resolve on their own after rest. On clinical evaluation, his visual acuity OU was 20/20 and IOP measured with Goldmann applanation tonometry was 14 and 16 mmHg in RE and LE respectively. Central corneal thickness (CCT) measured with Anterior Segment OCT was 479 and 475 microns in RE and LE respectively. Slit-lamp biomicroscopy OU revealed clumps of fine pigmentation on corneal endothelium (Krukenberg spindle) quiet anterior chamber and pigmentation on the posterior lens capsule (Zentmayer line) in RE.

Gonioscopy OU showed the presence of dense trabecular pigmentation in all quadrants (Sampaolesi line) and a concave configuration of the iris. On fundus examination, the optic nerves appear normal in both eyes. He underwent PRK 9 months ago with excellent postoperative uncorrected visual acuity (UCVA) OU 20/20. Prior to PRK, a detailed ocular examination showed a clear cornea with no pigments, a clear lens, normal IOP (with Goldmann applanation tonometry), a normal fundus and corneal tomography (Pentacam, Oculus) was within normal limits in BE. However, gonioscopy was not performed since IOP, anterior chamber depth and fundus examination were within normal limits. His UCVA was maintained at 20/20 OU until his last follow-up visit with a refractive surgeon. For evaluating early glaucomatous changes, Humphrey visual field (HVF) analysis using SITA Standard 24-2 and Optical coherence tomography retinal nerve fiber analysis (OCT-RNFL) (Carl Zeiss Meditec, Dublin, CA) were assessed and found to be within normal limits. A diagnosis of PDS was made and he was asked to follow up for IOP monitoring and clinical optic nerve head evaluation every 3 months. Also, HVF and OCT-RNFL will be repeated regularly as deemed appropriate. Gonioscopy should be included in the routine preoperative examination of patients undergoing kerato-refractive procedures. PDS patients undergoing laser vision correction should be counseled well about the need for regular follow-up to diagnose early signs of pigmentary glaucoma.