Restricted Access

You must be logged in to view this content.

Management of severe early onset keratoconus

$currentPage/@nodeName

Mark Hinds
BScApp(Optom) P/GCertOcTher BScApp(HMS) P/GBScHons FBCLA
Brunswick Optical, New Farm QLD

Keratoconus is like many diseases, with the age of onset often a marker of both the progression rate and the severity of the end stage.

EH was referred to me from a tertiary eye hospital for management of his high degree of corneal ectasia. My definition of corneal ectasia and keratoconus for record-keeping partly involves measuring the apical radius of curvature and power of the cornea at that point.

Obviously, other markers such as geographic location, area, contour and concomitant ocular and corneal pathology help define the potential influence on both the starting point and potential end point of vision correction.

There are various definitions in the literature and the speciality contact lens sphere but my definition in its simplicity is:

  • mild <50 D apical curvature
  • moderate 50-60 D apical curvature
  • severe >60 D apical curvature

Initial presentation

EH first visited me at the age of 18 years with an old episode (dating back two years prior) of hydrops in the left eye with extensive corneal neovascularisation and typical unresolvable posterior breaks in Desçemet’s membrane visible with OCT imaging. Both corneas were thin, measuring OD 190 µm and OS 180 µm with the only therapeutic management of Patanol gtt bd OU. At the time of initial presentation, the right eye only was fitted (18-24/12 prior) with a Katt (series one) 16.50 mm RGP from a colleague with limited wear time and 360 conjunctival seal off (Figure 1) and now marginal apical clearance indicating ectasia progression.

CL 60  Figure 1
Figure 1. Torus periphery on a 16.50 mm RGP

 

Vision measured CF without lenses in either eye and customised topographical tangential curvature maps are in Figure 2.

CL 60  Figure 2
Figure 2. Customised tangential curvature maps

 

We fitted EH with an 18.50 mm mini-scleral RGP in the right eye only with parameters of:

7.00/18.50/12.50/15.25/-7.25  (6/12) (Sag 6,675 µm apical clearance 106 µm), Harmony plus material

CL 60  Figure 3
Figure 3. Fine slitlamp cross-section of the RGP apical clearance

 

When referring back to the tertiary eye hospital, it was decided to put this young man on a systemic immunosuppressant (Imuran—azathioprine) to prepare him for a left eye corneal (PK) transplant. Figure 4 shows the left eye on slitlamp.

CL 60  Figure 4A
Figure 4A. Old hydrops left eye, with extensive corneal neovascularisation to 65 per cent of inferior cornea

During this waiting period, the patient decided that he would like to drive a motor vehicle as he lives in the country and travels great distances. We made a well-counselled decision to fit his left eye also with a mini scleral RGP to help him achieve his best vision for driving in the country. In-room trials achieved vision circa the right eye’s BCVA even with the stromal haze and neovascularisation well inside the pupil margin.

We often use the central corneal thickness/corneal oedema as a marker of endothelial integrity and subsequently a pass/fail criteria for large diameter RGP wear for patients with suspicious endothelial function/post graft. After a four-hour in-practice trial, the CCT as measured with OCT did not significantly change (< 5%). The left eye was fitted with:

7.70/18.50/12.50/15.25/-5.50 (6/12) (Sag 6,178 µm apical clearance 210 µm), Harmony plus material

It was fortuitous that we fitted the left eye as very soon after, the right eye also developed hydrops.

CL 60  Figure 4B

Figure 4B. Acute hydrops day 1

CL 60  Figure 5 CL 60  Figure 6
Figures 5 and 6. Hydrops day 14

CL 60  Figure 7
Figure 7. Hydrops day 30

 

The figures speak for themselves with an extreme hydrops reflected also from CCT going from baseline 190 µm to 1,890 µm at day 14, and at day 30 490 µm. This stimulated the corneal specialist to perform a partial (60 per cent) and temporary (2/52) tarsorrhaphy. Therapeutic management included Pred Forte qid OD stat for 3/52 then bid, Timolol bd OD, and Bion Tears q1h.

At the time of writing this report (6/52 from onset), the right cornea is clearing slowly and we will assess the RGP wearing status on resolution. The left eye is now his good eye and EH uses the 18.50 mm diameter RGP conservatively for 4-10 hours per day.

Discussion

Although we practise in a conservative, step-wise approach to keratoconus/corneal ectasia management, in this instance challenging the left eye with an 18.50 mm RGP was of infinite benefit to this patient. If we had not fitted this young man’s left eye, he would have been left with count fingers vision. We will continue to monitor the left eye for any markers of corneal stress and reassess the right eye post hydrops once settled.

All news may not be bad, with the upside being a reduction in corneal power and increase in rigidity secondary to stromal scarring. Often extreme corneal ectasias force our hand to challenge our clinical boundaries and we have to consider all available options.



Like us on Facebook



Latest Tweets




Recent Comments