Late development of ectasia or corneal warpage secondary to continuous wear of a SiH lens?

Dr Langis Michaud

Dr Langis Michaud graduated from School of Optometry of the Université de Montréal in 1986 where he also obtained his Master’s Degree in physiological optics. He is also graduated in public health ( 3rd cycle) from École Nationale d’Administration Publique in Montréal. He has been Fellow of the American Academy of Optometry since 1989 and Cornea and Contact Lens Diplomate since 1994.

Dr Michaud practices at Université de Montréal since 2001, mainly in contact lenses and anterior segment diseases. He had been involved in numerous clinical studies for pharmaceutical and contact lens companies and sits on the advisory board of a number of these firms. For more than 10 years he was a visiting professor at the Université de Paris-Sud (France) and is currently involved in teaching/educational  activities at the Vision Care Institute (Jacksonville, FL).

Dr Michaud has published numerous articles in peer-reviewed journals and publications or professional reviews. He holds a regular chronicle in L’optométriste (Association des optometrists du Québec) on eye diseases and in Clinical and Refractive Optometry (Medicopea) on contact lenses. He is a member of the editorial board of the latter publication and a reviewer for Eye. He also authors monthly chronicles in lay press on vision development and children’s vision.

Finally he is actually developing a unique longitudinal study project on ocular manifestations of Fabry’s diseases and Mucopolysaccharidosis disorders.

Because of his expertise he has often been invited to speak in Europe, Asia, and United States. He is a regular speaker at the American Academy of Optometry  Ellerbrock.

History

A Caucasian female, age 46, was referred to the Clinique Universitaire de la Vision (University of Montreal) for corneal topography measurements. The referring optometrist suspected corneal warpage secondary to continuous wear of Focus Night and Day contact lenses.

The patient had ceased to wear her contact lenses 3 weeks prior to the visit, complying with the recommendation of her optometrist. Her chief complaint while wearing contact lenses was fluctuating and reduced vision at distance, specifically at night. This symptom appeared several months earlier and was slowly deteriorating over time. The patient admitted to over-wearing her lenses, keeping them in her eyes for more than a month at a time. She had been wearing this lens type since 2000. During this time, each pair of contact lenses lasted for approximately 8 weeks, depending on the discomfort felt at the end of the wearing schedule. She had no glasses and relied only on her contact lenses to correct her ametropia. Her general health was good and she was taking anti-depressive medication (Effexor™) on a regular basis.

Objective Results

The only noteworthy ocular finding was left eye dominance at distance. The retinoscopy findings were:

OD -2,75 -1,50 x 180 and OS -1,50 -1,25 x 165

Refractive findings were:

OD -2,50 -1,00 x 180  20/20 and -1,50 -1,25 x 175  20/20-1 OS with an addition of +1,00 at near (0,5 M at 40 cm).

No previous records were available. Her contact lens prescription (OD -2,25 OS -2,00, BC 8,4) appeared to be a spherical equivalent approach with a slight under-correction on the non-dominant eye (OD) to improve near vision.

The topographic maps (Medmont) are attached. The Simulated K values were:

OD 44,1 x 44,6 @ 130 and OS 43,2 x 44,6 @ 85.

E values were:

0,61@127 and 0,82 @37 for OD and 0,66@85 and 0,89 @ 175, which are beyond the normal range of eccentricity values.

The left eye map exhibited corneal warpage with a protrusion in the lower third of the cornea, which could possibly be diagnosed as insipient keratoconus. The right eye exhibited less corneal warpage, mainly affecting the central area.  

The only positive slit lamp biomicroscopy was a grade 1+ papillae on the upper tarsal conjuctiva. There was no visible fluorescein staining of the cornea or conjunctiva, which was not surprising as the lenses had not been worn for 3 weeks.

MC OD initial	MC OS initial
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MC OD final	MC OS final
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Diagnosis

There were 2 possibilities: corneal warpage secondary to overwear of continuous wear high-Dk silicone hydrogel lenses or late development of keratoconus. This warpage was considered moderate to low, and may have decreased from the time the patient discontinued lens wear.

Plan

Corneal warpage resolves habitually within 3 weeks but can take up to 6 months to a year for severe cases. Complete restoration can be considered when topographic maps and refraction have the same results at 2 consecutive visits.

If this was warpage from lens wear, it may have been due to a combination of tight fit and continuous wear of higher modulus lotrafilcon A material; however, the corneal irregularity may have been due to the presence or development of keratoconus and independent of lens wear. We decided that it was not appropriate to prescribe spectacles at that stage, because of the possibility of further corneal changes.  Instead, we refit the patient with high-Dk toric silicone hydrogel lenses and limited wearing time to daily wear .

The following lenses and parameters were prescribed:

Acuvue Oasys for Astigmatism:  OD -2,50 -0,75 x 180; OS -1,50 -1,25 x 180 (BC 8,6/ 14,5)

Lenses were centered, with limited movement (0.5 mm upon blinking), with no rotation. There was no restriction on push-up. Visual acuity was 20/20-2 OD 20/20-1 OS and 20/20 o.u. at distance. Near vision was comfortable at computer distance.  A daily schedule of no more than 10 hours wear was recommended, along with lens replacement every 2 weeks. A hydrogen peroxide care regimen was prescribed (Clear Care, CIBA Vision).

The patient was re-examined a month later. Patient complained of poor vision at distance. Refractive findings were:

OD – 3,25 -0,75 x 10 (20/20) OS -2,25 -0,75 x 180 (20/20).

Corneas remained clear without staining or any adverse sign from contact lens wear. New toric lenses were prescribed according to the new refraction and the patient was re-examined 3 months later.  The final findings were:

OD -2,50 -1,25 x 170 (20/20)  OS -1,75 -2,25 x 180(20/20). Sim K values were OD 43,90 x 45,20 @ 68 and OS 43,5 x 45,25 @ 82.

E values were OD 0,61@68; 0,82@158 and OS 0,43@82; 0,88@172.

These topography measurements were similar to the original measures, with the eccentricity values remaining outside the normal range. 

The Acuvue Oasys lens prescription was changed to:

OD -2,25 -1,50 x 170 and OS -1,75 -2,25 x 180

Spectacles were prescribed to allow the patient to be free of contact lenses periodically. Continuous or extended wear was not recommended.  

Discussion /conclusion

This case illustrates how useful topographic mapping is in the evaluation and the follow-up of contact lens patients. This case was followed for about 4 months.  There was little change in corneal shape, suggesting that the corneal distortion may not have been caused by the high modulus lenses, but it’s as likely that the patient has some form of permanent corneal irregularity based on the eccentricity values.  The patient has pretty good visual acuity with spectacle lenses, which is consistent with the patient’s low level of corneal distortion.

High modulus lenses can alter corneal shape but the corneal distortion in this case was unlikely to have been caused by the long-term extended wear of the high modulus silicone hydrogels, since little change in corneal topography was observed over 4 months of follow up care.