Grouped vesicles noted in annual exam

Issue: August 2016

ByAmanda M. Tompkins, OD

A 46-year-old African-American female presented to the eye clinic for an annual eye exam.

Her last eye exam was 2 months prior, at which time she presented with foreign body sensation in the left eye. She was wearing distance-only glasses through which she was seeing well and she reported no visual complaints. She had a diagnosis of myopia, astigmatism, presbyopia, posterior polymorphous corneal dystrophy (PPMD) of the left eye and diabetes mellitus.

Subsequently, she had a non-metallic, “sand-like” foreign body removed successfully, with appropriate follow-up. She was released after the corneal abrasion healed and was told to schedule her annual diabetic eye examination before leaving the clinic.

At her annual exam, she reported her last medical exam was within the last 6 months but was unsure as to the date. She also reported that her doctor was following her for diabetes mellitus and hypertension for 5 years and high cholesterol for 3 years. Her medications included omeprazole, lisinopril, metformin, meloxicam and potassium, and she reported no known drug allergies. She was using no eye drops currently but had finished a short course of Moxeza (moxifloxacin HCl, Alcon) 2 months prior during her foreign body incident. Her family medical history was negative, and her social history was unremarkable.

Her entering acuities were 20/20 OD and 20/20 OS. Gross confrontational visual fields were noted to be full-to-finger-count in both eyes. Her refractive correction was -2.75 D -0.75 D x 075, 20/15 OD and -1.25 D -0.50 D x 085, 20/15 OS with +1.25 D add, 20/20 OU. Her pupil examination was unremarkable with pupils that were equal, round and reactive to light with no signs of relative afferent pupillary defect in either eye. Ocular motilities were full range of motion in each eye.

Slit lamp biomicroscopy in the left eye revealed small patches of grouped vesicles with an adjacent horizontally linear opacity approximately 6 mm in length as well as a vertically orientated, scalloped band in the mid-temporal endothelium approximately 6 mm in length.

The patient’s slit lamp biomicroscopy examination was unremarkable in both eyes except for the left corneal endothelium, which revealed small patches of grouped vesicles with an adjacent horizontally linear opacity approximately 6 mm in length as well as a vertically orientated, scalloped band in the mid-temporal endothelium approximately 6 mm in length. Mild nuclear sclerosis was noted of the crystalline lenses in both eyes.

Goldman tonometry had revealed IOPs of 14 mm Hg OD and 14 mm Hg OS at her last eye exam. Unfortunately, the patient insisted that she needed to go to work and had no time for IOP readings to be taken on this examination, against professional recommendation. The patient also refused dilation and was advised to return within 1 month for her annual diabetic eye examination.

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Based on the patient’s history of PPMD dating to her first examination at the clinic in 2009, the diagnosis remained for PPMD. It was believed that although foreign body sensation can be a symptom of PPMD secondary to epithelial defects, her chief complaint of foreign body sensation 2 months prior to this annual examination was incidental and not related to PPMD.

The patient was reminded of potential complications of PPMD, including probable stability of the condition but possible corneal swelling, resulting in a decrease in vision and a greater risk of recurrent corneal erosions. She was advised to begin routine lubrication to reduce her risk of erosions. She was diagnosed with compound myopic astigmatism, presbyopia and diabetes mellitus with a return to clinic date for the coming month to complete her dilated fundus evaluation.

Differential diagnoses

Differential diagnoses for PPMD include Fuch’s endothelial corneal dystrophy, congenital hereditary endothelial dystrophy and various metabolic diseases affecting corneal transparency.

PPMD is a dystrophy affecting Descemet’s membrane and endothelium of the cornea. Histological examination reports of the involved cells indicate that the pathophysiology of the disease is secondary to erroneous cell differentiation during development. The cells in the region of disease have differentiated into cells that hold characteristics consistent with those of epithelial cells, namely, that they contain keratin and are tightly connected to one another. The cells can also migrate to the areas of trabecular meshwork resulting in increased ocular pressure and the possible development of secondary glaucoma. Migration of these cells is possible because, unlike true endothelial cells, these epithelial-like cells retain their ability to divide. This represents the disease entity in that the normal endothelium is a single layer of cells that lose their ability to undergo miotic activity.

Clinical characterization

The disease is characterized clinically by opacities at the layer of Descemet’s membrane and endothelium of the cornea. These opacities are typically bilateral but often asymmetric. They can vary in their appearance and can present as vesicles, bands or polymorphous opacities. The presentation of vesicles is a result of the islands of abnormal cells surrounded by normal endothelial cells. The areas that are more band-like may represent areas of thickened Descemet’s membrane.

Associated findings upon ocular examination can include iris and anterior chamber angle abnormalities. Specifically, the iris can present with atrophy and corectopia and can have anterior adhesions to the posterior cornea, modifying the structure of the anterior chamber angle and, therefore, its function. Secondary glaucoma, corneal edema, keratoconus, non-keratoconic anterior and posterior corneal steepening, and Alport syndrome are all associations of PPMD. Regarding Alport syndrome, PPMD is among the spectrum of findings for the syndrome, with others including hearing loss and progressive renal failure.

Genetic disorder

PPMD is a genetic disorder with autosomal dominant inheritance. It is diagnosed at a wide range of ages because of its highly variable presentation, both on examination and symptomatically. Typically, when a patient presents in childhood, the disease is more severe, whereas if the patient presents in adulthood, he or she is usually mildly symptomatic and has a more stable disease state. Some patients are completely asymptomatic.

PPMD may be confused as part of the iridocorneal endothelial spectrum (ICE). The presentation of iridocorneal adhesions, glassy membranes and pupillary ectropion can be misleading in the diagnosis of PPMD. However, these findings in PPMD are rare and not characteristic, as they are in ICE syndromes. ICE is usually associated with glaucoma, and PPMD can be associated with glaucoma but not as frequently. Other differentials include other corneal dystrophies, degenerations, metabolic corneal disease and interstitial keratitis.

Typically, the patient is asymptomatic for PPMD and, therefore, the corneal findings present on routine ocular examination. However, if the patient does present with symptoms secondary to complications, they can range from mild blurred vision to significant visual loss, photophobia, ocular irritation, foreign body sensation, tearing and prescription changes that are not expected secondary to corneal steepening.

There is no treatment indicated for PPMD when it is asymptomatic and mild; however, it would be prudent to obtain gonioscopy and topography as baseline testing during routine examination of these patients. It rarely progresses to a more severe state once stabilized. If the disease progresses, it can lead to corneal edema secondary to endothelial under-action, recurrent corneal erosions or corneal scarring. Sufficient lubrication with a tear supplement may decrease discomfort and reduce the risk of recurrent corneal erosion. Mild corneal swelling may be treated with topical hypertonics. If corneal transplant is required due to scarring, the condition will often recur in the donor cornea.

This patient’s management

While our patient was not initially diagnosed on this visit, we were able to assess the stability of her PPMD and establish that the foreign body sensation she experienced 2 months prior was in fact due to a physical foreign body in her left cornea. The right cornea was evaluated for any signs of the dystrophy, and none were observed.

Sufficient lubrication during the day and at night would be advisable in this patient, as her condition is mild, stable and asymptomatic. Upon her follow-up examination, gonioscopy and topography should be performed for baseline data.

References:
Bozkurt BF, et al. Optom Vis Sci. 2015;92(11):e414-419. doi: 10.1097/OPX.0000000000000714.
Dahrouj M, et al. Posterior polymorphous corneal dystrophy. University of Iowa Health Care website. http://webeye.ophth.uiowa.edu/eyeforum/cases/208-PPMD.htm. Posted February 23, 2015. Accessed July 27, 2016.
Jang MS, et al. Vision Research. 2014;100:88-92. doi:10.1016/j.visres.2014.04.007.
Kaiser PK. Cornea/dystrophies. Massachusetts Eye and Ear Infirmary: Illustrated Manual of Ophthalmology. 3rd ed. Elsevier Saunders; 2003.
Krachmer JH. Trans Am Ophthalmol Soc. 1985;83:413-475.
Laganowski HC, et al. Br J Ophthalmol. 1991;75(4): 212-216.
O’Neill MJF. Corneal dystrophy, posterior polymorphous. Online Mendelian Inheritance in Man. http://www.omim.org/entry/609141. Posted January 5, 2005. Updated March 31, 2016.
Savige J, et al. Clin J Am Soc Nephrol. 2015;10(4):703-709. doi: 10.2215/CJN.10581014.

For more information:
Amanda M. Tompkins, OD, is an instructor at Southern College of Optometry. She can be reached at atompkins@sco.edu.
Special acknowledgment to Dr. Cynthia Heard for her diagnosis of the condition on the patient’s initial visit to the clinic.

Disclosure: Tompkins reported no relevant financial disclosures.