Download outline25152

Grand Round : A unique case of corneal warpage secondary to continuous wear of a
silicone hydrogel lens.
Subjective
M.C. is a Caucasian Female of 46 y.o. referred to the Clinique Universitaire de la Vision
(U of Montreal) for topography. She is a computer worker. The referent had suspected
corneal warpage secondary to continuous wear of her Focus Night and Day contact lenses
and was looking for topographic mapping of her corneas to confirm his diagnosis.
At the moment of her visit, the patient had ceased to wear her contact lenses for 3 weeks,
complying with the recommendation of her optometrist. Her chief complaint was
fluctuating and reduced vision at far and at night. This symptom appeared several months
ago and was slowly deteriorating over time. Patient admitted to overwear her lenses,
keeping them in eyes for more than a month at a time. She had been wearing this type of
contact lenses since 2000. During this time, each pair of contact lenses lasted for 8 weeks
in average, depending on the discomfort felt at the end of the wearing schedule. She has
no glasses and relies only on her contact lenses to correct her ametropia. Her general
health is good and she is taking anti-depressive medication (Effexor™) on a regular
basis. Past ocular and general family history are not contributory.
Objective
Entering visual acuity without contact lenses are 20/200 OD, OS and OU. There is no
strabismus and ocular motilities are smooth and complete in all gazes. Pupillary reflexes
are normal without any defect. Ocular dominance is established with OS as dominant at
far.
Retinoscopy gives OD -2,75 -1,50 x 180 and OS -1,50 -1,25 x 165. Refractive findings
are 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 for near vision (0,5 M at 40 cm). We were not able to compare these findings with
previous results since no previous records were available at the clinic and her optometrist
did not provide this information. Her contact lens correction (OD -2,25 OS -2,00, BC 8,4)
is different but could represent a spherical equivalent approach to compensate for her
ametropic condition with a slight under correction on the non dominant eye (OD) to
favour near vision.
Topographic maps (Medmont) are recorded and Sim K values are OD 44,1 x 44,6 @ 130
and OS 43,2 x 44,6 @ 85. E values are 0,61@127 and 0,82 @37 for OD and 0,66@85
and 0,89 @ 175 which represent abnormal findings considering the normal e value of the
cornea (0,45). The left map highlights more a corneal warpage with a bulging area seen
in the lower third of the cornea (pseudokeratoconus). The right eye shows a small corneal
warpage affecting mainly the central area.
Slit lamp biomicroscopy reveals normal lids without belpharitis. Both corneas were clear,
without edema nor microcysts neither neovascularization. There was no visible
fluorescein staining on the cornea neither on the conjunctiva. There was no hyperemia
anywhere on the anterior segment. The only noticeable findings was a grade 1+ papillae
on the upper tarsal area.
Ocular fundus are observed without dilation and found within normal limits. Goldman
tonometry measurement indicates 12 mm Hg o.u..
Assessment
Corneal warpage secondary to overwear of continuous high-DK silicone hydrogel lenses.
This warpage is considered moderate to low, probably already reduced compared to its
original state considering that the patient was not wearing her contact lenses for 3 weeks
prior to this evaluation.
PLAN
To restore the cornea to its original profile is the first goal of the treatment. Corneal
warpage resolves habitually within 3 weeks but can take up to 6 months for severe cases.
Complete restoration is considered when topographic maps and refraction gives the same
results on 2 visits made at a different time.
In this particular case, the warpage does surely not come from the lack of oxygenation
provided to the cornea as it is the case habitually on contact lens patients wearing
moderate to low-DK materials. The warpage found here is probably more related to the
higher modulus of the lotrafilcon A material and a tight fit. Overwear of contact lenses
could have play a role in this process as well.
Considering the limitations of the patient without appropriate visual correction, and
taking in account that to make a pair of glasses would not be appropriate because of the
visual fluctuation that goes along the corneal restoration, it is decided to refit temporarily
the patient in high-DK toric silicone hydrogel lens, to limit the wearing time and to
strongly recommend to do not wear them overnight.
Acuvue Oasys for Astigmatism are selected and the following parameters are prescribed:
OD -2,50 -0,75 x 180; OS -1,50 -1,25 x 180 (BC 8,6/ 14,5). Lenses are centered, well
positioned and without any rotation. There is no restriction on push-up and a 1,5 mm
movement upon blinking. Visual acuity is 20/20-2 OD 20/20-1 OS and 20/20 o.u. at far.
Near vision is comfortable at computer distance. A daily schedule of wear of no more
than 10 hours is recommended and the patient is told to discard the lenses every 2 weeks.
Hydrogen peroxide care regimen is prescribed.
The patient is seen back a month later and the cornea show some improvement at this
time. Patient complaints of bad vision at far. Refraction findings are OD – 3,25 -0,75 x 10
(20/20) OS -2,25 -0,75 x 180 (20/20). Cornea remained clear without staining nor with
any adverse sign from contact lens wear. Topographic maps show more symmetrical
patterns. New toric lenses are provided according to the new refraction.
Patient was followed for 3 months. It took that time to get stabilized results for both
topographic maps and refraction. The final findings are: OD -2,50 -0,50 x 10 (6/6)
OS -2,25 -0,75 x 5 (20/20). Sim K values are OD 43,25 x 43,87 @ 100 and OS 42,5 x
43,25 @ 85. E values were more aligned with the standard findings.
Since the patient get used to the 2 week-disposable modality, Acuvue Oasys lenses are
prescribed, a spherical one on the right side (-2,50) and a toric one on the left side (-2,25 0,75 x 180). A pair of glasses is prescribed in order to allow her to remove her contact
lenses periodically. Continuous or extended wear are strictly forbidden even if the
modulus of the Oasys is lower than the N& D lenses one and, upon our knowledge, never
been associated with corneal warpage.
Discussion /Conclusion
High DK contact lenses were introduced in the market mainly to provide more oxygen to
the cornea. This case reports illustrates the fact that even with the highest oxygen
permeability possible, some drawbacks can occur based on other parameters of these
products.
Especially with the first generation of Si-Hy lenses, practitioners have to pay attention to
the fitting of the contact lenses, their behaviour on the ocular tissue and to consider other
parameters than oxygen permeability to achieve the optimal fit. Modulus of the material
can initiate mechanical adverse reaction such as GPC, SEAL and corneal warpage.
Tighter lenses tend to compress the cornea and can contribute to mold the cornea.
Ametropic shift after Si-Hy refit were attributed to material modulus more than to the
higher oxygen level available for the corneal tissue.
Patients with corneal warpage are most often asymptomatic but some could compliant of
visual acuity fluctuation, discomfort and contact lens intolerance. Majority of cases will
be resolved within 3 weeks but some patients can take up to 6 months to restore their
corneal and refractive conditions.
Finally, this case illustrates how useful topographic mapping is in the evaluation and the
follow-up of contact lens patients.
---------------------