GP Lens Case Grand Rounds Troubleshooting Guide

Post Radial Keratotomy (RK): Custom Soft Lens Correction: Marsha M. Malooley, OD, FAAO, FSLS

Background

A 64 year male presented for a contact lens evaluation and fitting. He recently saw a corneal specialist for a complete eye examination. He had radial keratotomy performed in May 2013 OU. He desired a soft contact lens alternative to improve his vision over his current soft daily disposable toric contact lenses. He wore his contact lenses about 50% of the time, in particular when interacting with clients, social occasions, and golfing. The patient was taking Restasis BID OU along with preservative free artificial tears BID OU.

Both contact lenses centered well with less than 5-10 degrees rotation to the right OD and 10 degrees rotation to the right OS. Movement was about .5mm with blink OU. Four RK incisions were present OD and OS. No presence of superficial punctate keratopathy OU. 1+NS was present OU.

Testing Procedures, Fitting/Refitting, Design & Ordering

Visual Acuities (with soft toric contact lenses)

OD: 20/30⁺² (blurry and fluctuating with blink)
OS: 20/30^-2 (shadowed and fluctuating with blink)

Manifest Refraction:

OD: -0.75 -2.00 x 060 add +2.75 20/25 (ghosted)
OS: -1.75 -1.50 x 110 add +2.75 20/25 (ghosted and doubled)

Topography (Simulated Keratometry):

OD: 39.03@45;  37.83@135deg  (1+distortion)
OS: 40.06@120; 38.69@30deg  (1+distortion)

Side profile of cornea was oblate and matched the “post surgical” profile on the fitting guide.

Initial Fit

OD:
Kerasoft IC
Base Curve: 8.6
Periphery: steep 2
Diameter: 14.5mm
Power: plano

Initial Evaluation: no rotation, good centration and comfort, movement .5mm-1mm

Over Refraction: -1.00 -3.25 x 030  VA 20/25 stable with blink

OS:
Kerasoft IC
Base Curve: 8.6
Periphery: steep 2
Diameter: 14.5mm
Power: plano

Initial Evaluation: no rotation, good centration, mild overall lens awareness compared to OD, movement 2mm

Over-Refraction: -3.25 -1.25 x 150  VA 20/25 stable with blink

The increase in lens awareness and excessive movement both indicated the periphery was too flat. A steeper periphery was indicated OS.

Lens Parameters Ordered:

Kerasoft IC

Follow-Up Care/Final Outcome

At his two week contact lens follow up examination, the patient reported more stable vision and improved ghosting with the new contact lenses. Both lenses centered well. Rotation was 5 degrees left OD and no rotation OS. He felt more dependent on his over-the-counter reading glasses. An over refraction of +0.50 OD was found to improve his distance and intermediate vision and a new contact lens was ordered with the adjusted power. No changes were made OS.

Discussion/Alternative Management Options

Alternative contact lens options were considered for this patient including corneal gas permeable lenses and scleral lenses. Although corneal GPs would have provided sharper vision, part-time wear would have made adaptation more challenging. Scleral contact lenses were recommended as an alternative, in particular considering the patient’s history of dry eyes.

Kerasoft IC is one of several custom soft contact lens designs available for patients with irregular astigmatism, including post-surgical as well as keratoconus. Diagnostic fitting sets are necessary to properly fit these designs. In many of the custom soft designs, the center thickness of the lens is increased to mask corneal irregularity. Proprietary designs with varying peripheral curves and optical zone diameters are used to fit both prolate and oblate corneas. In addition, the vast range of both spherical and cylindrical powers satisfy most prescriptions.

Supplemental Readings

1. Su S, Johns L, Rah MJ, Ryan R, Barr J. Clinical performance of Kerasoft® iC in irregular corneas. Clinical ophthalmology (Auckland, NZ) 2015;9:1953.
2. Gumus K, Kahraman N. A new fitting approach for providing adequate comfort and visual performance in keratoconus: soft HydroCone (Toris K) lenses. Eye & Contact Lens: Science & Clinical Practice 2016;42(4):225-230.
3. Malooley, Marsha and Charles Faron. “Contact Lenses Options for Irregular Corneas” Contact Lens Spectrum, May 2011.

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