Repeatable Measurements Detect Glaucoma Progression in Eyes With Keratoprosthesis

Corneal Transplant
Corneal transplant two weeks after surgery. The sutures are 1.5 thousandth of an inch thick nylon. The image clearly shows the diameter of the donor cornea which came from an eye bank.
The exact mechanism of glaucoma associated with KPro is not known, and patients undergoing this procedure often have complex corneal problems and several comorbidities.

Using 10-2 visual field testing and retinal nerve fiber layer (RNFL) thickness analysis are reliable and repeatable methods of monitoring  glaucoma progression in eyes with Boston type 1 keratoprosthesis (KPro), according to a study published in Cornea. 

Investigators analyzed the reliability of routinely used clinical tests for patients with glaucoma who underwent KPro (n=16) and penetrating keratoplasty (PK) (n=14). They performed a 10-2 visual field with size V stimulus, estimated intraocular pressure (IOP) measurements by palpation, and measured retinal nerve fiber layer (RNFL) thickness via optical coherence tomography. A second observer also estimated the IOP and visual field analysis was repeated. Researchers obtained color photographs of the optic disk, and 2 masked observers determined cup-to-disk ratios at 2 separate time points.

The team noted that the inter-rater agreement of palpated IOP estimate was moderate for KPro eyes (ICC=0.47) and fair for PK eyes (ICC=0.27). They observed high test–retest reliability for visual field and RNFL thickness in both KPro and PK eyes (ICC=0.80 for both). The inter-rater agreement of cup-to-disk ratio assessments was also substantial in both KPro and PK eyes (ICC=0.62 and 0.70, respectively).

“[S]everal glaucoma tests can give repeatable results in KPro and PK eyes, particularly 10-2 visual field testing using size V stimulus and RNFL thickness measurement using SD-OCT,” according to the researchers. “Cup-to-disk ratio assessments using color photographs showed varying repeatability within the same grader and relatively high variability between graders in eyes with KPro.”

Limitations of the study include the small sample size, lack of objective IOP measurements, and possible lack of quality imaging in some KPro eyes.


Akpek EK, Karakus S, Yohannan J, et al. Reliability of several glaucoma tests in patients with Boston Type 1 keratoprosthesis. Cornea. 2022;41(3):310-316. doi:10.1097/ICO.0000000000002800.