CLINICAL

  ANTERIOR

A GLARING PROBLEM

ARE CATARACTS THE CULPRIT OR SOMETHING FAR MORE SERIOUS?

JOSH JOHNSTON, O.D., F.A.A.O.

A 62-YEAR-OLD white male presented with a chief complaint of glare from bright lights at night while driving. His ocular history revealed a previous diagnosis of cataracts (one year ago) by a different doctor. (The cataracts weren’t removed because they were classified as mild.) Given the patient’s previous diagnosis, I presumed his glare was likely due to cataract progression. The patient’s BCVA was 20/30 OU, and his glare was 20/200 OD and 20/400 OS. Exam findings revealed surprisingly minimal cataracts that were not affecting the patient’s vision. Anterior segment evaluation showed corneal guttae on his endothelium consistent with Fuchs’ endothelial corneal dystrophy.

Here, I discuss the etiology, symptoms, clinical signs, diagnosis/management options, as well as the ICD-10 codes for Fuchs’ endothelial corneal dystrophy.

ETIOLOGY

Fuchs’ endothelial corneal dystrophy is a common visually significant corneal dystrophy. It is an inherited autosomal dominant dystrophy, which is bilateral and usually asymmetrical. The condition occurs most commonly after age 50 and affects women more than men.

The pathophysiology of Fuchs’ corneal dystrophy is a primary malfunction of the endothelium. This malfunction then induces widespread, irreversible death, or loss, of endothelial cells. Cell death results in an influx of aqueous, which can lead to stromal corneal edema, corneal erosions and consequential reduced vision.

In the condition’s early stages, Descemet’s membrane thickens, prompting guttae to form. Next, polymorphism takes place, and endothelial cell size increases. In moderate and advanced stages of the condition, bullae can be seen under the epithelium, and corneal edema and Descemet’s membrane folds appear. The condition’s final stage includes endothelial cell loss and Descemet’s membrane thickening.

Note the corneal guttae with subsequent stromal edema and pigment deposits on the posterior endothelial surface.

SYMPTOMS

• Blurred vision (worse during morning hours)

• Decreased color perception

• Decreased vision

• Foreign-body sensation

• Glare

• Ocular discomfort upon waking

• Visual distortion

CLINICAL SIGNS

• Endothelial pigment dusting or pigment deposition on the posterior endothelium surface (early stages)

• Focal thickenings of Descemet’s membrane form corneal guttae that are best viewed with direct illumination (early stage of disease)

• Endothelial cell size increase (moderate disease)

• Cell loss in the endothelium causes the appearance of holes, best seen with retroillumination (advanced disease)

• Endothelial cell functional loss resulting in bullous keratopathy (advanced disease)

• Stromal edema with Descemet’s membrane folds (advanced disease)

DIAGNOSIS/MANAGEMENT

To diagnose Fuchs’ endothelial corneal dystrophy, the following should be used:

• VA testing. The more severe the endothelial cell damage and loss, the more vision will be limited. Decreased VA usually ranges from 20/30 to 20/50.

• Pachymetry. Use this to assess corneal thickness, which increases as the disease progresses. A thickness of 600 µm usually indicates the condition.

• Endothelial microscopy. Use this to measure endothelial cell counts, which help in arriving at a diagnosis. The average normal cell counts are 2,000 to 3,000 with an average of 2,400. (You can do serial readings to test for progressive cell loss.)

Management for Fuchs’ endothelial corneal dystrophy includes:

• OTC palliative options. Sodium chloride hypertonic ophthalmic solution 5% or 5% ointment used every three to four hours daily and q.h.s., respectively, aids in increasing vision, as these drugs treat corneal edema. Both can safely be used long term in mild cases (surgery is not indicated). A more frequent dosage can be used in the advanced stage of the disease when a greater amount of corneal edema is seen, though surgery hasn’t been indicated.

• Therapeutics. Bandage contact lenses and topical NSAIDs can be used to treat the painful bullae, seen in the condition’s advanced stages, that require surgical intervention. NSAIDs can be used q.d. or b.i.d. for one to two weeks.

• Surgery. When the above treatment options fail and the patient’s vision has decreased, a surgical referral should be considered. In the past, penetrating keratoplasty, Descemet’s stripping endothelial keratoplasty and Descemet’s stripping automated endothelial keratoplasty were used. Today, ophthalmologists opt for Descemet’s membrane endothelial keratoplasty (DMEK), which completely eliminates the stromal part of the donor by transplanting only Descemet’s membrane and endothelium after the patient’s diseased corneal tissue is removed. This transplant is 15µm thick and results in better average VA vs. the other procedures postoperatively early on, as well as long term. Also, the graft rejection rates are below 1%, reveals Ophthalmology. And, there’s less post-operative refractive error, making irregular cornea contact lens fittings a thing of the past. (See “Future Surgeries,” left.)

THAT PATIENT

I educated the patient on his Fuchs’ endothelial corneal dystrophy diagnosis. He abruptly interrupted in a fearful tone, “do I need surgery?” He then mentioned that his mother had bilateral corneal transplants 30 years ago, and that he “didn’t want to go through what she had experienced.” I explained to him that I didn’t think he’d need surgery “at this time” and that I would be prescribing palliative OTC treatments and observing him at regular follow-up visits to determine whether visual deterioration continued. If a vision reduction continued, I told the patient he would need DMEK, but that it was far superior to what his mother had to endure. I provided the patient with an educational video about DMEK, and he was at ease with proceeding with it, if needed. The patient is being monitored annually and has not had to under-go surgery. OM

DR. JOHNSTON practices at Georgia Eye Partners. He focuses on ocular surface disease and has extensive experience in co-managing cataract and refractive surgery patients. Email him at drj@gaeyepartners.com, or visit tinyurl.com/OMcomment to comment.