GP lens eye Rounds

POST-SURGICAL: Corneal Crosslinking Case

HPI: 21 year-old Caucasian male with history of mild keratoconus, OS > OD. Routine follow-up was not consistent over time, but upon more frequent examination with corneal tomography at age 23, progressive keratoconus was confirmed OS. US Food and Drug Administration (FDA) – approved corneal cross-linking (CXL) was performed OS following insurance review and approval.
CC: Severe blur OS, with glare and shadows particularly at night, which had become progressively worse over the last few years.
Modifying factors: Patient presented with no vision correction, as a soft contact lens trial fitting performed years prior was not successful. Corneal cross-linking (CXL) had been performed OS, a few months earlier.

OD: 20/25+1

OS: 20/60

OD: pl +0.50 x 030, 20/20-3

OS: -1.00 +2.50 x 170, 20/20-3

Lids/Lashes	cl, WNL OU
Conjunctiva/sclera	trace papillae UL and LL
Cornea	Mild inferior ectasia OD; mild ectasia with mild haze/scars and Vogt’s striae centrally OS

OD: 42.5/46.6 D, Kmax 55.4 D; CCT 454

OS: 45.4/51.4 D, Kmax 66.3 D; CCT 419

Figure 1: Corneal tomography (OD left and OS right)

Anterior Segment Optical Coherence Tomography (OCT)
- AS OCT (performed six weeks after CXL OS)(Figure 2).

Figure 2: OCT images: Demarcation line within corneal stroma OS is visible, demonstration remodeling process following CXL.

Patient elected to proceed with scleral lens fitting OS after GP trial was unsuccessful. No contact lens was necessary in the fellow eye, as the patient was satisfied with his uncorrected VA OD. Topical allergy eye drops were prescribed to address chronic allergic conjunctivitis and the patient was counseled to avoid eye rubbing due to its potential impact on keratoconus progression.

A scleral lens was designed and dispensed to the patient after successful application/removal training, about six months following CXL OS. 1st lens parameters: 17.5 mm OAD, 8.5 OZD, 5.53 sag, 7.67mm BCR, -3.50D, 200 microns toricity, Optimum Extra material (Contamac).
After wearing the 1st lens for three weeks, it was determined to be slightly tight all around and had minimal central clearance of less than 100 microns after settling for seven hours. The next lens was loosened 30 microns all around the landing zone and the central vault was increased by 150 microns. The 2nd and final lens: 17.5 mm OAD, 8.5 OZD, 5.65 sag, 7.34mm BC, -5.50D, 190 microns toricity, Optimum Extra material.
BCVA with scleral lens OS was 20/20- with significant improvement to halos and glare as compared to spectacles. A spectacle prescription was also released for use as needed.

Frequent and careful follow-ups are indicated in young patients with mild keratoconus (1).
Due to the COVID-19 pandemic, this patient’s follow-up visit was delayed for 18 months. Once progressive keratoconus was confirmed, it took another six months before CXL could be performed due to challenges with insurance approval.
Cross-linking should be discussed with patients and guardians early, so they are aware of intervention for progressive disease.
Asymmetry in keratoconus between eyes can mask disease progression, as patients may be fully functional with good vision from one eye alone.
Contact lenses can be fit or re-evaluated about one month after CXL, or slightly longer (two months) in new lens wearers due to possible micro-trauma from the training process (2).
Prescription in glasses and soft contact lenses often change due to corneal remodeling after CXL; while changes may also occur in GPs and scleral lenses; it is often less than in glasses or SCLs.

Ferdi AC, Nguyen V, Gore DM, Allan BD, Rozema JJ, Watson SL. Keratoconus Natural Progression: A Systematic Review and Meta-analysis of 11 529 Eyes. Ophthalmology. 2019 Jul;126(7):935-945.
BLOG: How to prepare patients for contact lens wear after cross-linking (healio.com)