Clinician answers patients’ questions on specialty contacts, ocular surface
Elise Kramer, OD, a private practitioner from southern Florida, compiled questions she receives most often from patients, along with her answers, for Primary Care Optometry News.
She specializes in ocular surface disease and specialty contact lens fitting.
Question: Why do contact lens wearers seem to prefer scleral lenses over gas-permeable (GP) lenses?
Kramer: Although scleral lenses and corneal GP lenses have several features in common, such as measures of visual correction and quality of vision, a number of important differences make scleral lenses a better choice for many patients.
Both scleral lenses and corneal GP lenses give novice wearers a certain sensation of “awareness,” but GP lenses tend to be more uncomfortable or harder to adapt to initially. The weight of the GP lenses is supported entirely by the cornea, whereas scleral lenses are fit independently of the cornea and rest on the sclera. Corneal GP lenses move with every blink, which may cause visual instability and/or fluctuations. Scleral lenses are designed to fit with little or no lens movement during blinks and are, therefore, more stable on the eye. On very irregular corneas, corneal GP lenses may move so much that they even fall out of the eye in certain positions of gaze. When scleral lenses are well adjusted, it is almost impossible for this to happen. Lastly, dust and particles can get under a GP lens with just a small gust of wind, causing severe discomfort and tearing. This is highly unlikely with a well-adjusted scleral lens. For all these reasons, scleral lenses are often preferable to corneal GP lenses. GP lenses definitely have their place, however, and corneal GP lenses are a suitable treatment in many situations.
Question: What is the cure for dry eye disease?
Kramer: I tell patients that, unfortunately, dry eye disease cannot be “cured;” it is a chronic condition. But it can be adequately managed. Managing dry eye disease depends on the underlying cause.
Based on the Tear Film Society Dry Eye Workshop II report, two distinct types of dry eye can be identified: aqueous deficient dry eye and evaporative dry eye. Dry eye can also be a mix of the two types. The root causes of dry eye, whether of the aqueous-deficient or evaporative type, are inflammation and hyperosmolarity.
Treatments range from eye drops, eyelid hygiene (in office or at home), prescription drops targeting different inflammatory mediators in the dry eye cycle, meibomian gland expression (manual or device-assisted), warm compresses, serum tears, amniotic membranes, punctal plugs, omega-3 supplements and scleral lenses. Again, the choice of treatment depends on the causative condition.
Question: What is the best treatment for keratoconus?
Kramer: I tell patients that for mild cases or early stages of keratoconus, eyeglasses or soft contact lenses may provide clear and comfortable vision. For highly irregular corneas, however, eyeglasses or soft lenses do not usually lead to a good outcome. I tell them that many optometrists and ophthalmologists recommend scleral contact lenses for patients with keratoconus. Scleral lenses do not touch the compromised cornea; they are fitted in a way to vault the cornea and are, therefore, more comfortable for most patients with keratoconus. The space between the back of the lens and the front surface of the cornea is filled with a nonpreservative sterile saline solution. This solution maintains a constant reservoir of fluid between the lens and the cornea to ensure constant lubrication. Moreover, this fluid layer compensates for surface irregularities, helping to improve vision. Scleral lenses can provide the comfort of soft lenses with the optical quality of GP lenses. Also, scleral lenses are designed to fit with little or no lens movement during blinks, making them more stable on the eye than traditional corneal GP lenses. Scleral lens designs currently available are considered the best option to improve vision and comfort.
I also tell patients that collagen cross-linking (CXL) has been shown to be an effective treatment for keratoconus and post-LASIK ectasia. This minimally invasive in-office procedure strengthens the cornea by creating strong bonds (cross-links) between corneal collagen fibers. The goal of the procedure is to prevent further progression of the keratoconus or ectasia. Clinical research has shown that cross-linking not only halts the progression of keratoconus but also flattens the cornea and improves vision. Collagen cross-linking involves the instillation of riboflavin (a B vitamin) drops on the cornea after removing the epithelium. Once saturated with riboflavin, the cornea is irradiated with ultraviolet A light for about 30 minutes. Most patients still need to wear specialty contact lenses or scleral lenses following the procedure.
Question: How can the effects of myopia be reduced naturally?
Kramer: Engaging in outdoor activities is associated with a slower progression of myopia is what I tell my patients and parents. It may be a good idea for children with progressive myopia to spend more time outdoors.
Question: What is the best treatment for myopia?
Kramer: I inform my patients that people with myopia are at higher risk for retinal detachments (and other blinding retinal complications) and glaucoma. Early treatment of the condition can slow its progression and help prevent the most serious consequences. “Myopia management” is the umbrella term used to describe the methods for slowing the progression of myopia. Several distinct treatments can help.
Orthokeratology (ortho-K) lenses are customized through the use of a corneal topographer. Patients wear the lenses while sleeping, and the lenses gently and gradually reshape the corneal surface. In the morning, patients can remove the lenses and enjoy clear vision throughout the day without wearing glasses or contact lenses.
Distance center multifocal soft contact lenses have zones throughout the lenses that reduce peripheral hyperopic defocus, reducing the stimulus for axial elongation of the eye.
Low-dose atropine (0.01%) has recently emerged as an effective approach to slowing the progression of myopia. It has minimal effects on pupil size, accommodation and near vision. It is, therefore, a great option for children with increasing myopia who do not want to use contact lenses.
Question: Is it dangerous to use ortho-K lenses? What are the benefits?
Kramer: Orthokeratology is as risky as wearing any oxygen-permeable contact lenses overnight. It is important for patients to follow the instructions for lens wear and care to prevent microbial keratitis.
Ortho-K lenses also enhance natural vision for recreation, sports and leisure; provide good unaided vision for pilots, policemen, firefighters and others whose work requires better visual acuity; and provide visual freedom for playing sports without wearing eyeglasses or conventional contact lenses.
This treatment can be used at any age and is completely reversible and free of surgical risk. It is one of the most effective methods to slow progressive myopia in children.
Question: What are some of the up-and-coming new technologies you’re excited about?
Kramer: I’m excited about topography beyond the limbus, in-office mold/impressions to design scleral lenses, completely customizable haptics for scleral lenses, correction of higher-order aberrations, empirical designs for ortho-K, drug-releasing contact lenses and UV protective contact lenses.
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Elise Kramer, OD, is a residency-trained optometrist practicing at the Miami Contact Lens Institute in Miami and Weston, Fla., who specializes in ocular health and disease, ocular surface disease, and regular and specialty contact lens fitting. In recent years, she has created a unique scleral lens practice devoted to restoring quality vision and ocular comfort to patients who have been affected by keratoconus, refractive surgical complications and corneal transplant surgery.