GP Lens Case Grand Rounds Troubleshooting Guide

Exposure Keratopathy Secondary to Facial Nerve Palsy: Pam Satjawatcharaphong, OD, FAAO, FSLS

Background

A 50 year- old Caucasian female, presented to the clinic for a comprehensive eye examination. Her ocular history was significant for a congenital acoustic neuroma, a non-cancerous tumor that grows on cranial nerve VIII between the brainstem and the inner ear¹. She underwent acoustic neuroma surgery 25 years ago to remove the tumor, but due to the proximity of the mass to cranial nerve VII, a permanent right facial paralysis resulted from the procedure (Figure 1a). She had gold weights implanted in her upper right eyelid, which were cosmetically noticeable (Figure 1b). Her systemic history was significant for acid reflux disease, and the only medication she took was Protonix twice daily. Her family ocular history was unremarkable. This case documents an alternative treatment method—a scleral gas permeable (GP) contact lens—to manage the patient’s exposure keratopathy and poor vision secondary to a facial nerve palsy.

Test Procedures, Fitting/Refitting, Design and Ordering

Visit #1: Comprehensive Examination

The patient presented with a chief complaint of severe constant dryness of her right eye.  Her primary therapy was to use artificial tears throughout the day and lubricating ointment at night before sleeping. She also complained of poor vision in her right eye that was not well corrected by her habitual spectacles. She came seeking alternative treatment options, and her primary goal was to improve her ocular comfort.

Uncorrected Visual Acuities

OD: Counting fingers 
OS: 20/300

Habitual Spectacles

OD: -3.75 -0.50 x 008 (20/200)
OS: -4.75 -1.00 x 145 (20/15)
Add +1.25D

Visual acuity (VA) of the right eye was not improved with manifest refraction, and the best corrected VA remained 20/200 OD and 20/15 OS.

Extraocular muscle movements were full and unrestricted and her pupils were equally round and reactive to light with no noted afferent pupillary defect. She had no stereopsis, and showed suppression OD. The patient also missed 3 of 6 HRR color vision plates OD, whereas she missed no plates OS. Non-contact tonometry was 16 mmHg OD and 17 mmHg OS, and confrontation visual fields were full OU. Her blood pressure was 120/90 mmHg. 

Anterior Segment Evaluation

The patient requested to defer her dilation to a follow-up visit. At this examination the patient was diagnosed with ptosis secondary to gold weight implants, lagophthalmos, and Grade 4+ exposure keratopathy with associated keratinization of the lower half of the cornea OD. Her reduced vision, suppression, and color vision test errors OD were attributed to the poor quality of the tear film and the opacification of the cornea in that eye. The patient was referred to the contact lens service to be fit into a scleral lens to alleviate her dry eye symptoms of the right eye. The patient was advised to return for a dilated fundus exam the following week.

Visit #2: Ocular Health Examination

The patient returned the following week to complete her dilated fundus examination. Due to the asymmetry of the cup-to-disc ratios, this patient was classified as a low risk glaucoma suspect based on her optic nerve head appearance.  It should be noted that the fundus views OD were difficult due to the hazy cornea. A full glaucoma work-up was scheduled based on the optic nerve appearance, and recommended testing included GAT, pachymetry, stereo fundus photographs, and optical coherence tomography.  The anterior segment findings were consistent with the previous visit, and the patient was advised to keep her scheduled contact lens appointment. Due to the corneal exposure of the right eye, the patient was scheduled to return for a scleral lens fitting of the right eye only in an attempt to improve comfort.

Visit #3: Scleral Lens Fitting

The patient returned one month after her initial visit to begin a scleral lens fitting for her right eye.  Her presenting distance VAs through her spectacles were 20/400 OD and 20/20- OS.  Her keratometry readings were 39.75@085/39.87@175 with grade 3+ distortion OD and 41.87@090/42.50@180 with no distortion OS.  The right eye cornea showed grade 3+ to 4+ staining and keratinization of the inferior half, and the left eye cornea was unremarkable. 

Corneal Topography

Medmont corneal topography employs a placido disk principle, which uses reflections to measure the pre-corneal tear film surface¹².  The patient’s topography revealed both irregular astigmatism and poor tear film quality in the right eye due to rapid break-up of the placido rings (Figure 3).

Diagnostic Lens Selection

A Jupiter standard scleral lens design was chosen for the right eye. The two standard diameters are 15.6 mm and 18.2 mm. Due to the nature of the patient’s condition, the larger 18.2 mm diagnostic lens was chosen in order to achieve more coverage of the ocular surface and afford better protection. The standard Jupiter design has a prolate shape and the reverse geometry design has an oblate shape. Based off the topography, it was determined that a prolate design would be appropriate.

Slit lamp evaluation of the diagnostic lens showed 300 mm corneal apical clearance, limbal clearance, trace edge lift at the 3 o’clock and 9 o’clock lens margins, and no blood vessel blanching. The over-refraction was -7.50 DS (20/40); however, as the patient wanted to continue to wear her current spectacles over the contact lens to protect her eyes, the contact lens power that was ordered was adjusted to compensate for her spectacle lens power.  The fourth peripheral curve was steepened slightly due to the edge lift noted with the diagnostic lens. 

Final Lens Order

Patient Consultation and Education

Visit #4: Dispense Appointment

The patient returned two weeks later for a dispensing of her first scleral lens. Visual acuity of the right eye while wearing her scleral lens with her spectacles on top was 20/40+2. Over-refraction was +0.25 DS (20/30). The scleral gas permeable lens created a regular corneal refractive surface which improved visual acuity. The fit still showed 300 mm central clearance and full limbal clearance (Figure 3) with no vessel blanching and good scleral alignment (Figures 4a-4d).

The patient was instructed on proper application and removal technique using a large DMV plunger.  A sample of Boston Simplus GP solution was dispensed for lens cleaning and storage, along with instructions to purchase Unisol 4, a preservative-free saline solution, which would be used to fill the scleral GP lens prior to application (solution was not discontinued at the time of fitting). Although the lens covered the entire cornea, the oxygen transmissibility of the material was high and there was adequate tear exchange, and few hypoxic side effects with these lenses have been reported. The patient was instructed to allow for an adaptation period when first wearing this lens—starting with 6 hours gradually increasing wear time until full-time wear was achieved. The patient was also told not to sleep in the lens, so in order to continue to provide corneal protection, the patient used a lubricating ointment for her right eye before bedtime.

Follow-up Care and Final Outcome

Visit #5: Two Week Follow-up

The patient returned two weeks after the initial scleral lens dispense, and had been wearing the lens for nine hours prior to her appointment. She reported wearing the lens daily for an average of 16 hours and had no comfort complaints related to lens wear. She used rewetting drops occasionally to clear away mucus strands that developed on her lens surface due to her incomplete blink. Her visual acuity of the right eye with the contact lens and the glasses at this visit had improved to 20/20-1 compared to the initial dispense appointment. The over-refraction with the presenting lens was still +0.25 DS, but the patient did not appreciate a significant difference when it was demonstrated to her with a loose trial lens and preferred to stay with the power of her presenting contact lens. 

The central clearance was estimated with a slit lamp to be approximately 200 mm indicating lens settling had occurred; otherwise there was no change to the appearance of the lens fit from the previous visit. However, some mucus strands were noted on the surface of the lens.  There was a slight improvement in the appearance of the right eyelid ptosis when comparing the eye without the lens (Figure 5a) to the eye with the lens (Figure 5b).  Since the sagittal depth of the scleral lens was significant, it acted as a slight crutch for the upper eyelid.  Grade 3 diffuse staining of the cornea from exposure keratopathy was noted—an improvement from her initial presentation. The improvement in visual acuity at this visit compared to the previous visit was attributed to the healing of the corneal surface which was no longer exposed during the patient’s waking hours. 

The patient reported being very happy with the scleral lens and noticed a considerable decrease in her dry eye symptoms. She was told to continue using rewetting drops to clear away mucus strands that developed, or to remove, clean, and refill the lens as needed during the day. She continued to use a lubricating ointment for her right eye after she removed the lens before going to sleep.

Visit #6: Two Month Progress Check

At her two-month progress check, the patient reported stable vision and comfort with an average daily wear time of 12 hours. Visual acuity of the right eye at this visit was 20/20-2, and the over-refraction was plano DS. She had been wearing the lens for six hours prior to the appointment, and the appearance of the fit was similar to the previous visit, except for mild blanching over a shallow temporal pinguecula.  Slit lamp examination revealed grade 2+ to 3 staining from exposure keratopathy over the inferior portion of the cornea (Figure 6), and appeared to show continued improvement from initial presentation.

The patient’s pinguecula was shallow, and since the blanching was focal and very mild, it did not cause any bulbar hyperemia or other adverse effects so no lens parameter changes were made. The patient was instructed to continue her habitual routine and return in six months.

Visit #7: Six Month Progress Check

The patient returned for her six-month progress check and continued to enjoy good comfort and vision with an average daily wear time of 12 hours. Visual acuity OD at this visit was 20/20-3, and the over-refraction was plano. She had been wearing the lens for eight hours prior to her appointment and the appearance of the fit was unchanged compared to her prior visit. Slit lamp examination revealed grade 1+ staining with sodium fluorescein over the inferior portion of the cornea primarily near the limbus (Figure 7), which was an even further improvement from her previous visits. The patient was scheduled to return in another six months for her annual comprehensive eye examination and contact lens evaluation.

Discussion/Alternative Management Options

Facial nerve palsy is a disorder of cranial nerve VII, which controls movement of the muscles in the face.  Damage to this nerve typically causes unilateral facial weakness or paralysis, although in about 10% of cases the paralysis is bilateral¹.  Symptoms experienced by the unilateral palsy patient include drooping of one side of the face, drooling, dry mouth, loss of sense of taste, inability to close the affected eye, and twitching of the facial muscles.  Ocular sequelae of this condition include ptosis, lagophthalmos, exposure keratopathy, epiphora, ulceration of the cornea, and decreased vision¹.  This condition can result from a number of different etiologies including surgery for an acoustic neuroma or parotid tumor, but when it is idiopathic it is termed a Bell’s Palsy^1,2.

Upon ocular examination, afflicted individuals will exhibit a number of signs, including punctate epithelial erosions of the inferior portion of the cornea, epithelial breakdown, stromal melting which may lead to perforation, secondary ocular infection, and scarring². Recommended treatment of this condition has been dependent on the nature of the corneal exposure, and includes a wide range of options. Conservative management has included palliative treatment with non-preserved artificial tears throughout the day with a lubricating ointment at night, taping the eyelid shut, or bandage contact lenses³. Medical management that can temporarily improve eyelid closure has been documented with the use of botulinum toxin injection of the levator palpebrae muscle^4,5. Permanent corneal exposure has been managed with surgical methods, including tarsorrhaphy, palpebral spring implants, or gold weights inserted in the upper eyelid^6,7,8.  Of the aforementioned methods, gold eyelid weighting continues to be the most widely used method of management despite a high rate of complications, including poor cosmesis from visibility of the weight under the skin, migration, extrusion, allergy, and astigmatism^9,10. 

The patient in this case opted to try scleral lenses as gold weight implantation and aggressive lubrication had not been effective in reducing her symptoms. Taking into account the considerable risk of complications with medical and surgical modes of management, scleral contact lenses present a less invasive and very effective way to treat patients suffering from the symptoms of paralytic lagophthalmos and exposure keratitis.

The first scleral contact lenses date back to 1888 in Germany and were made from blown glass. With the introduction of polymethylmethacrylate (PMMA) material in 1936 ideas for a more successful scleral lens design were being formulated, but problems arose with the low oxygen transmissibility of the material and the limited lens reproduction capabilities of that time¹³. In the 1970s-80s with the advent of gas permeable materials, the production of a scleral lens that would be physiologically safe for the eye became a much more real possibility¹⁵. 

With current day lathe technology and highly oxygen transmissible material (Dk ≥100), scleral lenses have been successfully manufactured and have become an invaluable tool for many contact lens practitioners. The popularity of these lenses stem from the ability to provide crisp and stable vision with GP lens material, but to also provide excellent comfort as the lenses do not touch the sensitive corneal surface. 

The most common indication for prescribing scleral GP lenses is to correct irregular astigmatism from corneal conditions such as keratoconus and pellucid marginal degeneration, or after corneal surgeries such as penetrating keratoplasty or radial keratotomy. Treatment of ocular surface disease with scleral lenses is a less familiar indication that can be overlooked, but is a very useful therapeutic tool in the management of severe dry eye conditions¹⁵, as was demonstrated in this case report.

Scleral lenses bear entirely on the conjunctiva overlying the sclera and completely vault the cornea. This design creates a fluid reservoir between the cornea and the contact lens (Figure 8), which can be ideal for patients with dry eye symptoms, such as exposure keratopathy in this particular case.  The lens will both bathe the cornea in fluid and protect the vulnerable portion of the cornea from desiccation due to evaporation of the tear film¹⁶. 

An appropriate fit for a scleral lens will show complete cornea clearance, complete limbal clearance, and alignment with the sclera. Excessive edge lift or blanching of blood vessels indicates poor alignment, and the peripheral curves of the lens can be adjusted so that the lens edge is flush with the conjunctival surface.  

Lens seal off is one of the most problematic complications that can occur with an improper lens fit. Scleral lenses create a semi-seal that holds a tear reservoir between the cornea and lens, but should allow for slow tear exchange. When lens seal off occurs, there is circumlimbal congestion and lack of tear exchange, which must be addressed by adjusting the peripheral curves that land on the sclera.

Another one of the more common obstacles with scleral GP lenses is avoiding anatomical landmarks where the lens lands, such as pingueculae, conjunctival cysts, or filtering blebs.  Fortunately, in this case the patient’s pinguecula was shallow and not causing any adverse symptoms. However, for some patients if the pinguecula is particularly large or high, this can present a problem. Ways to address this problem include significantly flattening the peripheral curves that land on the sclera without flattening excessively and allowing bubbles to enter the corneal chamber, increasing or decreasing the overall diameter of the lens to avoid the landmark. Alternatively, a notch, focal vault, or impression technology can also be utilized to avoid misalignment.

Other complications that can occur with the use of a scleral lens include rebound bulbar conjunctival hyperemia or impression ring upon removal, clouding of the tear reservoir between the eye and the contact lens, or bubble formation.  While some of these problems indicate that there may need to be an adjustment to the fit of the lens, others are not fit issues and simply require some patient education. Educating patients about normal versus abnormal sequelae while wearing scleral lenses is important.

Scleral lenses tend to settle down with longer wear time, and may sink down into the conjunctiva. Rebound bulbar redness after lens removal may occur in patients who are still becoming accustomed to the application and removal process. This is typically not a problem as it should resolve fairly quickly after the lens is removed. However, extreme persistent hyperemia may indicate a tight fit. A slight impression ring on the scleral conjunctiva upon lens removal after a full day of wear is acceptable as long as there is no blanching during lens wear and no injection of the conjunctiva¹⁶. An impression ring with associated conjunctival hyperemia or congestion can indicate a tight fit or excessive lens flexure. A tight fit requires adjustment of the peripheral curves to better align with the sclera and allow tear exchange. Excessive lens flexure can be minimized by increasing the lens center thickness or using a toric haptic design.

Tear reservoir clouding is a fairly common finding, and it can be very alarming if the patient is not informed ahead of time as in some cases it can significantly impair vision. This can be caused by misalignment of the scleral haptic, but if clouding is still occurring even with proper alignment, there are alternative options to help. For most patients, this typically occurs toward the end of the day, and the easiest way to manage this is to advise the patient to always have their lens solution and plunger with them in order to clean and refill the solution during the day as needed. Other methods of management include adding a few drops of viscous non-preserved solution into the lens before application as it may delay the need to replace the solution by slowing debris circulation inside the lens.

Air bubble formation is almost always a result of improper lens application technique and is easily remedied by reviewing the process with the patient. Occasionally bubble formation can occur if the lens does not land flush with the sclera and has areas of excessive edge lift. Ways to remedy this include steepening the peripheral curves, or in the cases of patients with toric scleras, ordering the lens with a toric haptic.

Despite a full 12-hour day of wear, this patient did not experience any negative side effects with scleral lens use, and only occasionally had to remove the lens during the day to clean and refill it. However, as each patient’s sensitivity and anatomy are different they should each be informed of the possibility of all these side effects occurring. There are possible adverse effects from scleral lens wear, such as corneal edema, corneal neovascularization, microbial keratitis, or contact lens related infiltrates or inflammation.  However, it is important to note that there is limited literature addressing follow-up of patients wearing these lenses long-term. It would be beneficial to perform studies collecting data regarding any complications that may result from wearing scleral lenses over long periods of time in order to have a more complete understanding of this technology, and thus enable practitioners to prescribe them with confidence. Scleral lenses present a viable alternative treatment option to manage both ocular surface diseases and decreased visual acuity that result from these conditions, but patients should be followed regularly to ensure that corneal physiological health is maintained while the patient is wearing scleral lenses.

References

1. Tasman, W, Jaeger, EA.  Duane’s Ophthalmology, 9th Edition, Philadelphia: Lippincott Williams & Wilkins, 2009.
2. Kanski, JK.  Clinical Ophthalmology: A Systematic Approach, 6th Edition, Philadelphia: Elsevier, 2007.
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4. Prell J, Rampp S, Rachinger J, et al.  Botulinum toxin for temporary corneal protection after surgery for vestibular schwannoma.  J Neurosurg. 2011; 114(2):426-31.
5. Bulstrode NW, Harrison DH.  The phenomenon of the late recovered Bell’s palsy: treatment options to improve facial symmetry.  Plast Recostr Surg.  2005; 115(6):1466-71.
6. Manodh P, Devadoss P, Kumar N.  Gold weight implantation as a treatment measure for correction of paralytic lagophthalmos.  Indian J Dent Res. 2011; 22(1):181.
7. Lessa S, Nanci M, Sebastia R, Flores E.  Treatment of paralytic lagophthalmos with gold weight implants covered by levator aponeurosis.  Ophthal Plast Reconstr Surg.  2009; 25(3):189-93.
8. Muller-Jensen K, Jansen M.  6 years experience with reversible and surgical upper eyelid weighting in lagophthalmos.  Ophthalmologe. 1997; 94(4):295-9.
9. Silver AL, Lindsay RW, Cheney ML, Hadlock TA.  Thin-profile platinum eyelid weighting: a superior option in the paralyzed eye.  Plast Reconstr Surg. 2009; 123(6):1697-703.
10. Bladen JC, Norris, JH, Malhotra R.  Indications and outcomes or revision of gold weight implants in upper eyelid loading.  Br J Ophthalmol. 2011 Oct 27.
11. Wang, M. Irregular Astigmatism Diagnosis and Treatment, Slack Inc, Thorofare NJ, 2008.
12. Zhu, M et al. Dynamics of ocular surface topography. Eye. 2007;21:624-32.
13. Mandell R. Contact Lens Practice, 4^th Edition.  Charles C. Thomas, Springfield IL, 1988.
14. Van der Worp E. A Guide to Scleral Lens Fitting. Pacific University College of Optometry, 2010
15. Severinsky B, Millodot M. Current applications and efficacy of scleral contact lenses—a retrospective study.  Journal of Optometry. 2010; 3(3):158-63.
16. Pullum, K, Buckley R. Therapeutic and ocular surface indications for scleral contact lenses. The Ocular Surface. 2007; 5(1):40-9.
17. Ehler JP, Shah CP. The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease. Baltimore: Lippincott, Williams and Wilkins; 2008.
18. Michaud, L, et al.  Predicting estimates of oxygen transmissibility for scleral lenses. Contact Lens & Anterior Eye. 2012; http://dx.doi.org/10.1016/j.clae.2012.07.004.

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