Central Corneal Thickness Peaks at 12 Months After Congenital Cataract Surgery

Mean central corneal thickness (CCT) peaks at 12 months, while intraocular pressure (IOP) remains within normal ranges through 24 months in both aphakic and pseudophakic eyes after congenital cataract surgery, a study published in Cornea shows. The investigators concluded that both CCT and IOP should be monitored closely in postsurgical patients for up to 12 months as both parameters may impact the ability to diagnose glaucoma.

Researchers tracked the CCT and IOP present in the both eyes of 76 pediatric patients who had unilateral or bilateral congenital cataracts and underwent lensectomy and limited anterior vitrectomy with a limbal approach at the Eye Hospital of Wenzhou Medical University, Hangzhou, China. They made the measurements of CCT and IOP at about 1 month, 3 months, 6 months, 12 months, and 24 months after the patient’s surgery. 

Comparing the 77 aphakic and the 42 pseudophakic eyes to the 33 eyes that did not have cataracts, they found that while CCT had increased from before the surgery to the measurement at 24 months in both phakic types, it was relatively stable (P =.783) from 12 to 24 months in the aphakic eyes and actually decreased over that time period in pseudophakic eyes (from 540.76 ± 49.40 mm to 531.56 ± 48.77 mm).

Intraocular pressure, on the other hand, remained within normal ranges for both phakic types even though it was significantly higher at 24 months (14.22 ± 2.30 mm Hg in aphakic) than it was before the surgery (12.25 ± 2.54 mm Hg). It did not change significantly over the course of the study in the pseudophakic eyes.

They also saw that CCT and IOP were positively associated (P <.001) in the aphakic and pseudophakic groups. 

“Because there is a correlation between CCT and IOP, abnormal corneal thickness may affect real IOP measurements,” the researchers said. “In turn, this may affect the diagnosis of glaucoma, suggesting that monitoring of refraction, axial length, and the optic nerve is very important after cataract surgery in children.”

Limitations of this study included the 18-month difference between the average age at surgery of the aphakic group compared to that of the pseudophakic group and that the aphakic group received dexamethasone for one week while the researchers tapered it over an additional 4- to 6-week period for the patients in the pseudophakic group.

Congenital cataracts are a major cause of visual impairment in pediatric patients and undergoing cataract surgery at this age may increase the risk of glaucoma, with the incidence of glaucoma among aphakic children at approximately 32%. The researchers said more studies to analyze the nature of the relationship between CCT and IOP could enhance postoperative care of pediatric cataract patients.

Reference

Chang P, Kou J, Zhang B, et. al. Postoperative changes in central corneal thickness and intraocular pressure in a prospective cohort of congenital cataract patients. Cornea. Published online August 24, 2020. doi: 10.1097/ICO.0000000000002480