Keratopathy
Keratopathy is a medical term describing abnormal changes of the cornea – a protective smooth layer covering the eye inside the eyelids. There are multiple problems and diseases that can cause keratopathy. They are divided by ophthalmologists into types based on mechanism causing it.
In this article:
- What Is keratopathy?
- Symptoms and signs
- Causes
- Types of keratopathy
- Band shaped keratopathy (BSK)
- Exposure keratopathy
- Striate keratopathy
- Whorl (vortex) keratopathy or cornea verticillata
- Bullous keratopathy
- Toxic keratopathy
- Diagnosis
- Ocular examination
- Eyelids
- Proptosis
- Systemic issues
- References
What Is keratopathy?
Keratopathy is a common eye disease that can be a component of a larger medical problem, such as diabetes or autoinflammatory condition. It can be aso caused by other parts of the eye not working right.
The worst outcome of the keratopathy is blindness, as cornea is a part of the vision apparatus transmitting the light rays inside the eye to be reflected on the retina. Normal cornea must be completely clear and moist to ensure good vision. Keratopathy leads to the changes in the quality of the cornea, sometimes irreversibly.
There are many treatments available, which restore the composition and integrity of the cornea. If this attempts fail, modern cornea specialists are able to perform a cornea transplant which has a high rate of success in rescuing person’s vision.
Ophthalmologists are the main specialists treating keratopathy. They work as a team with primary care and specialists, such as endocrinology and rheumatology, when the cornea problem is caused by a systemic disease.
Symptoms and signs
Cornea disease may go for a long time asymptomatic, while a person may present with a different complain or symptoms:
- Delayed healing after an eye surgery
- Droopy eyelids
- Face asymmetry with excessive tearing on one side
- Feeling of foreign body or “sand in the eye”
- Decreasing vision, blurry vision, double vision
Causes
Any process affecting permeability, structure and composition of the cornea will lead to keratopathy. While the initial agent causing eye problem may be different, an inflammation and dryness will eventually disturb layers of cornea causing deposits and scarring.
For example, the cause of band shaped keratopathy is an imbalance in the calcium and phosphate metabolism resulting in deposition of calcium phosphate crystals into the subepithelial Bowmans’s layer, epithelial basement membrane, and anterior stroma. This peripheral clearing is likely due to the absence of Bowmans’s membrane in the periphery or buffering capacity of limbal vessels that prevents the deposition of hydroxyapatite. Holes in the BSK gives it a swiss cheese appearance and is because of corneal nerves traversing the Bowman’s membrane.
Diabetes mellitus (DM) is one of the most common, deadly metabolic diseases worldwide. The incidence rate of DM has risen over the years and is expected to double by the year 2030. The hyperglycemic condition during diabetes has various implications on various tissues, and the most common complications witnessed during such conditions are retinopathy, nephropathy, neuropathy, and keratopathy.
Eye surgical procedures may cause damage of the cornea cells by laser burn or mechanical disruption. Multiple metabolic diseases cause cornea deposits of the lipids or other matter, which changes light reflective quality and affects vision. Keratopathy related to vernal keratoconjunctivitis is IgE mediated and TH2 cell-mediated reaction.
Infectious crystalline keratopathy is largely caused by biofilm-producing organisms and immune response with cytokine inflammation. The presence of biofilms protects the bacteria against sequestration, but causes changes of the optical cornea quality. In aqueous deficient dry eyes, lack of tear production results in excessive production of mucus by goblet cells. The epithelial injury along with the mucus debris results in filament formation.
Types of keratopathy
There are many factors that can negatively affect cornea quality and lead to the severe complications. It is of crucial importance to know what type if keratopathy is affecting your eyes to learn how to prevent possible vision loss.
Diabetic keratopathy.
Ocular complications from diabetes mellitus are common. Diabetic keratopathy, the most frequent clinical condition affecting the human cornea, is a potentially sight threatening condition caused mostly by epithelial disturbances that are of clinical and research attention due to its severity.
Diabetic keratopathy exhibits several clinical manifestations, including persistent corneal epithelial erosion, superficial punctate keratopathy, delayed epithelial regeneration, and decreased corneal sensitivity that may lead to compromised visual acuity or permanent vision loss.
Band shaped keratopathy (BSK)
This name of the keratopathy comes from an observation that changes in the cornea are band-like. The inflammation affecting cornea in this type of keratopathy is associated with systemic diseases:
- Hyperparathyroidism
- Vitamin D toxicity
- Sarcoidosis
- Nephropathic cystinosis
- Hypophosphatemia
- Paget’s disease
- Multiple myeloma
- Familial band-shaped keratopathy
- juvenile idiopathic arthritis
Eye diseases that also involve band keratopathy are:
- Uveitis
- Chronic herpetic keratouveitis
- Phthisis bulbi
- Keratoconjunctivitis sicca
Exposure keratopathy
Exposure keratopathy is a consequence of the inability to maintain uniform tear film distribution over the ocular surface. Tear film helps in maintaining the epithelial integrity and thus prevents any epithelial denudation. Abnormal tear film distribution over the ocular surface leads to dryness and inflammation. Causes of the exposure keratopathy are:
- Decreased corneal sensation and decreased blinking
- Proptosis
- Lagophthalmos (paralytic, cicatricial, nocturnal)
- Lid deformities (coloboma, cicatricial ectropion, post-surgical)
Striate keratopathy
Striate keratopathy is characterized by the presence of corneal edema with Descemet’s folds after cataract surgery in an eye with a relatively healthy and clear cornea and in the absence of obvious Descemet’s membrane detachment. The edema is maximum on day 1 and improves as the day passes off. Hypertonic saline in conjunction with topical steroids, helps edema clear off completely over weeks.
Corneas with pre-existing compromised but non-decompensated endothelial pumps are largely at risk of developing striate keratopathy. However, the use of excessive ultrasonic energy during phacoemulsification can cause this condition even in the cornea with absolutely normal endothelium. If a toxic substance permeates into the anterior chamber through the surgical incision during surgery, it can cause severe grades of inflammation (toxic anterior segment syndrome).
Whorl (vortex) keratopathy or cornea verticillata
Agents causing whorl keratopathy include amiodarone, chloroquine, hydroxychloroquine, phenothiazines, tamoxifen, indomethacin, and many other pharmacologic agents. Non-pharmacological conditions associated with whorl keratopathy include Fabry’s disease, multiple myeloma, Lisch corneal dystrophy, post- radial keratotomy, and other diseases.
Bullous keratopathy
This type of post-surgical cornea disease is divided into:
- Pseudophakic bullous keratopathy (PBK) is an endothelial cornea cell damage due to intervention (surgical or traumatic). Irreversible damage to endothelial cells manifests in corneal edema. The intraoperative damage caused to endothelium by instrumentation, ultrasonic energy during phaco, and exposing endothelium to toxic solutions leads to endothelial damage. Intense inflammationmay further cause toxic anterior segment syndrome, and raised intraocular pressure also add to the damage post-operatively.
- Aphakic bullous keratopathy (ABK) develops because of the inner lens absence or removal. Vitreous substance is the major insulting agent causing damage to the endothelium due to vitreo-corneal touch. This results in the death of endothelial cells and subsequent ABK.
Toxic keratopathy
This type is due to immune damage of the epithelium cells as a result of the allergic reaction of direct side effect of the medication:
- Dendritiform keratopathy may be noted due to polyquaternium-1 (preservative)
- Keratopathy related to vernal keratoconjunctivitis (VKC): The keratopathy is largely due to the mechanical effect of papillae and also due to the release of various cytokines.
- Keratopathy related to Stevens-Johnson syndrome (SJS)/ toxic epidermal necrolysis (TEN): Most of the cases of SJS or TEN are related to hypersensitivity reactions to a medication or its metabolite. Sulphonamides, analgesics, anti-epileptics, and many other drugs are implicated
- Amantadine was originally discovered as an anti-viral to treat influenza in the 1950s. In the late 1960s, it was discovered to be useful in treating tremors and dyskinesia associated with Parkinson’s disease and began to be widely used for this purpose. Today amantadine is prescribed for some chronic neurodegenerative and neurocognitive diseases. The mechanism of action of amantadine is largely unknown. Amantadine keratopathy is a term used to describe corneal edema and subsequent decrease in visual acuity that is assumed to be caused by the drug. Corneal edema typically resolves with discontinuation of the drug.
Diagnosis
Diagnosis of the keratopathy is made by an ophthalmologist. You may suspect the damage of the cornea by the symptoms in your eyes, but it is not advisable to self-treat without a professional eye exam.
History of the eye-related problems is crucial, as well as the other body problems. In addition to the slit lamp exam, lab tests are needed to rule out systemic diseases. It is important to bring other medical records with you, so an ophthalmologist can determine if an eye disease is related to the other problems with joints or genetic disease.
A history of the previous eye surgeries is extremely important. If you continue to see an ophthalmology surgeon who originally performed a cataract or LASIK procedure, you will ask for your records to be transferred to the cornea ophthalmologist.
Medical diagnosis of the severe environmental allergy may lead to the discovery of the vernal conjunctivitis; while a recent start of a certain medication will need an investigation from an expert allergist. It is important to discuss family history if your child is having unusual deposits in the cornea. This might indicate a rare genetic disease that was not diagnosed yet, but runs in the family.
If your child is having cornea disease, you will need to establish care with the pediatric ophthalmologist, who might refer you to other specialists.
Most of the diagnosis is made clinically with the exam of the eyes and the slit lamp examination of the cornea. A dye (lipofuscin) will be administered as an eye drops to determine if the cornea has ulcers or defects.
Ocular examination
- Visual acuity and refraction
- Cover test to look for any hypotropia and rule out any component of pseudoptosis
- Extraocular motility disturbance and any aberrant eyelid movements, abnormality of the eyelids
- Pupillary examination to look for Horner syndrome or 3rd cranial nerve palsy
- Examination to look for any giant papillary conjunctivitis or symblepharon
- Corneal sensation and dry eye evaluation as they can predispose to post-operative keratopathy.
- Fundus examination for features of retinal pigmentary degeneration
Eyelids
Eyelid mobility and anatomy will be examined to determine if the eye has complete closure. In the situations such as Bell’s palsy the face asymmetry and inability to close an eye or one side of the mouth is diagnostic.
The genetic defects and syndromes that affect eye structure will be first recognized in the hospital by a neonatologist. A pediatric ophthalmologist and geneticist will be consulted to recommend management.
Proptosis
Thyroid associated orbitopathy (TAO) is a common diagnosis encountered by ophthalmologists and oculoplastic surgeons. TAO has a varying clinical presentation that can include upper eyelid retraction, restrictive strabismus, proptosis, exposure keratopathy, and optic neuropathy. Graves disease causes bulging of the eyes and affecting eyelids, so the cornea is exposed to dryness. Control of the thyroid disease is essential in preventing cornea complications.
Systemic issues
Systemic diseases must be addressed whenever the keratopathy is symptom affecting the eye, not a separate entity. Diabetes control leads to better vascular function and provides the eye with needed nutrients. Rheumatoid arthritis treatment will lead to disease remission and prevent cornea dryness.
References
Keratopathy. Singh P, Tripathy K.2021 Feb 14. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan–.PMID: 32965824 Free Books & Documents. Review.
Diabetic keratopathy: Insights and challenges. Priyadarsini S, Whelchel A, Nicholas S, Sharif R, Riaz K, Karamichos D.Surv Ophthalmol. 2020 Sep-Oct;65(5):513-529. doi: 10.1016/j.survophthal.2020.02.005. Epub 2020 Feb 22.PMID: 32092364 Free PMC article. Review.
Current Understanding of the Progression and Management of Thyroid Associated Orbitopathy: A Systematic Review. Hodgson NM, Rajaii F.Ophthalmol Ther. 2020 Mar;9(1):21-33. doi: 10.1007/s40123-019-00226-9. Epub 2019 Dec 10.PMID: 31823232 Free PMC article. Review.