specialty contact lenses
Case Study: Scleral Lenses Post Glaucoma Surgery
Add another “notch” on your specialty contact lens belt by learning from this case
MELISSA BARNETT, O.D., F.A.A.O., F.S.L.S., SACRAMENTO, CALIF.
A 58-year-old Hispanic female was referred to me for a contact lens examination. She presented complaining of irritated eyes with her current hybrid contact lens and said that she reverted to soft lens wear in the left eye.
In addition, the patient had decreased vision, especially at distance when driving at night, and double vision with both eyes open when in a reclined position.
The patient’s medical history was significant for diabetes, hypertension, hypothyroidism and sleep apnea. Systemic medications included insulin, metformin, glimepiride (Amaryl, sanofi-aventis U.S. LLC), lisinopril, hydrochlorothiazide, levothyroxine and escitalopram (Lexapro, Actavis).
The patient’s ocular history was positive for dry eye disease, cataract surgery OD and primary open-angle glaucoma OD for which she had a type of stent inserted six months prior.
Following the implant OD, she developed hypertropia as well as alternating exotropia. (Persistent restrictive strabismus may occur with glaucoma drainage implants as a result of scarring between the rectus and oblique muscles, so this is not uncommon).
Ocular medications were brimonidine tartrate ophthalmic solution (Alphagan, Allergan) and dorzolamide hydrochloride-timolol maleate (Cosopt, Merck) b.i.d. OD.
The patient’s entering vision was 20/50+2 without correction OD and 20/50-2 OS with the soft contact lens.
Anterior segment examination revealed the stable glaucoma drainage device located superior temporal OD with a bleb over the plate. The tube was well covered and visible in the anterior chamber.
Both eyes exhibited corneal staining (1+ inferior punctate epithelial keratopathy). The posterior chamber IOL was stable OD. Mild nuclear and cortical sclerosis was present OS.
IOPs were OD 25mmHg and OS 21mmHg at 1:57 p.m. Optic nerve examination revealed vertical elongation of the disc with peripapillary atrophy OU. Myopic degeneration was present OU.
Scleral lenses, by virtue of their design, are an ideal option for patients who have irregular corneas, ocular surface disease and glaucoma.
Yes, a trabeculectomy, shunt, stent or glaucoma implant results in an irregular conjunctival surface. And yes, excessive pressure or a rubbing of the lens over tube shunts or valves may compromise IOP and lead to conjunctival and/or tube erosion, which can increase the risk of further complications, such as endophthalmitis.
That said, you can fit the scleral lens inside of conjunctival abnormalities by decreasing the lens diameter or creating a notch in the scleral lens to prevent pressure on the conjunctiva and contact with the surgical area. Such notches are also advantageous for other types of conjunctival abnormalities, such as an elevated pinguecula or conjunctival cyst.
Creating a notch in a scleral lens may sound complicated, but it is not. It requires five simple steps:
1. Measure the size (both height and width) of the conjunctival abnormality using a slit beam.
2. Measure the height and width of the conjunctival abnormality while the scleral lens is on the eye.
3. Mark the scleral lens with a permanent or dry erase marker while the lens is on the eye.
4. Measure the tracing on the lens after removing it from the eye.
5. Call the laboratory consultant to discuss the plan, and send the lens to the laboratory.
Recommended treatment for the 58-year-old female was non-preserved artificial tears, frequent breaks when reading and using a computer, good water intake, daily omega-3 fatty acid intake and scleral lenses for both eyes.
Lens parameters were OD 46.00D base curve (BC), 15.0mm overall diameter (OAD), 8.00mm optical zone diameter (OZD), +0.50D power, sag 4.35, 4mm notch (to insert superior temporal) and OS 46.00D BC, 15.4mm OAD, 8.0mm OZD, –13.00D power, sag 4.46 (intermediate/near).
The right lens was targeted for distance, and the left lens was targeted for intermediate/near to eliminate diplopia. I created a superior temporal notch in the right scleral lens (See Figure 1, page 30).
Figure 1: Creating a notch in a scleral lens requires five simple steps.
The patient’s VA at distance was 20/30 OD, 20/30+2 OS, 20/25-2 OU, and she reported good distance, computer and near vision, with J1+ OD and J1+ OS at near.
In addition, the patient said the lenses were comfortable. Both lenses fit well with good central apical clearance and good peripheral alignment. No blanching was present in either eye.
The scleral lens notch was correctly positioned superior temporal in the right eye and did not touch the glaucoma implant. The patient was able to wear the lenses for 15 hours each day.
IOP was checked multiple times during a three-month period and ranged from 16mmHg to 18mmHg in each eye.
When inserting a scleral lens, it is important to place it on the eye with the correct orientation. Therefore, make sure to inform the staff person who will be training the patient on scleral lens application and removal, as well as the patient, about the need for proper lens orientation.
Scleral contact lenses have changed many of my patient’s lives, including the one mentioned above.
With the availability of multiple designs, both patients and doctors are reaping the rewards of these lenses. OM
Dr. Barnett is a Principal Optometrist at the UC Davis Medical Center in Sacramento. She specializes in anterior segment disease and specialty contact lenses, lectures and publishes extensively on topics including dry eye, anterior segment disease, contact lenses, corneal collagen cross-linking and creating a healthy balance between work and home life for women in optometry. She serves on the Board of Women of Vision (WOV), Gas Permeable Lens Institute (GPLI) and The Scleral Lens Education Society (SLS). Dr. Barnett is a spokesperson for the California Optometric Association. She has worked with Acculens, Alcon, Alden Optical, Allergan, CooperVision, Nidek, and Vistakon. E-mail her at firstname.lastname@example.org, or send comments to email@example.com.