Snow Blindness
Photokeratitis- `welder's flash' or `snow blindness'.
The greatest retinal exposure to blue light UV occurs outside standing/walking in a field of snow without eye protection= exposure to levels exceeding occupational exposure limits.
Failure to wear ski goggles can result in several effects upon the eye, sometimes loosely referred to as `snow-blindness'.
Unusually intense reflection of light and UVR from the snow.
* Fresh snow reflects 85% of the UVR compared to only
* 1 or 2% from grass.
* Goggles with side-shields, or a closely fitting wrap-around design, the specification of 99% or 100% UV blocking.
* UV light can enter the eye from the sides and also by reflecting off the edges of the sunglasses. Therefore, side shields and overhead protection are critical and can be provided with wrap-around sunglasses or goggles.
* Polarising sunglasses protect against excessive glare.
Prevention of UV exposure
Protection:
* broad-brimmed hat or visor can help shield the eyes from both visible and invisible light
* The eyelids, the same as the skin elsewhere on the body, should be protected by use of a sunscreen.
* UV-absorbing spectacles.
Large frames and wraparound designs offer the greatest protection to both the eyes and the eyelids. UV-absorbing contact lenses are available from a number of lens manufacturers and are preferred to non-UVabsorbing materials in individuals who spend a lot of time outdoors. Since contact lenses may shield the cornea from UV light but offer no protection to the conjunctiva, sclera, or eyelids, they do not provide the same level of ocular protection against UV radiation exposure that spectacles do.
Most modern clear spectacle lenses are made of plastic (CR-39) or polycarbonate, and these materials absorb a substantial portion of UV-A radiation and almost all UV-B. Polycarbonate lenses have inherent UV blocking property. In addition they are thinner, lighter and shatter-resistant
* UV transmittance can be further decreased by the use of chromophores that can be incorporated into the lens material without affecting the transmission of visible light. The so-called photochromic or variable-tint lenses provide increasing protection against UV radiation as exposure increases, becoming darker with the stimulus of ultraviolet light and lightening when the light stimulus is removed. They represent the most physiologic modality for UV radiation protection based on level of exposure
Pterygium
A raised, wedge-shaped growth of the conjunctiva. Most common in tropical climates or spend a lot of time in the sun. Pterygia are conjunctival thickenings that may have blood vessels associated with them. They often have a triangular-shaped appearance.
Symptoms:
. Irritation
2. Redness
3. Tearing.
* nourished by tiny capillaries that supply blood to the tissue.
* For some, the growth remains dormant;
* In other cases it grows over the central cornea and affects the vision.
* As the pterygium develops, it may alter the shape of the cornea, causing astigmatism.
* If the pterygium invades the central cornea, it is removed surgically.
Since pterygiums are most commonly caused by sun exposure, protecting the eyes from sun, dust and wind is recommended. Instilling artificial tears liberally is also helpful to decrease irritation. In some cases, steroid drops are prescribed to reduce inflammation.
Pinguecula
Non-malignant, slow-growing proliferations of conjunctival connective tissue in the eye.
Pterygia, but not pingueculae, extend over the cornea.
* Common in adults
* Incidence increases with age.
* Pterygia are less common than pingueculae.
Pingueculae are seen as small, raised, thickenings of the conjunctiva.
May be yellow/grey/white/colorless.
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Since pterygiums are most commonly caused by sun exposure, protecting the eyes from sun, dust and wind is recommended. Instilling artificial tears liberally is also helpful to decrease irritation. In some cases, steroid drops are prescribed to reduce inflammation.
Pinguecula
Non-malignant, slow-growing proliferations of conjunctival connective tissue in the eye.
Pterygia, but not pingueculae, extend over the cornea.
* Common in adults
* Incidence increases with age.
* Pterygia are less common than pingueculae.
Pingueculae are seen as small, raised, thickenings of the conjunctiva.
May be yellow/grey/white/colorless.
Almost always to one side of the iris--not above or below--and usually nasal.
A pinguecula may develop into a pterygium.
The cause or causes of these disorders are unknown, but they are more frequent in people who live in sunny and windy climates and people whose jobs expose them to ultraviolet (UV) light (for example, farmers and arc welders).
Pingueculae and pterygia also occur in older people. It is thought these growths are the result of UV or IR light and irritation. It is also believed that prolonged exposure to these risk factors (that is, UV light) increases the chances of occurrence.
Symptoms:
Although some people with pinguecula constantly feel like they have a foreign body in their eye, most are asymptomatic. Because the lids can no longer spread the tears over a smooth area, dry areas may result. Some people with a pterygium are also asymptomatic; some feel like they have a foreign body in their eye. Because a pterygium can stretch and distort the cornea, some people acquire astigmatism from a pterygium.
An eye doctor (ophthalmologist or optometrist) can usually diagnose pingueculae and pterygia by external observation with a slit lamp. However, because pingueculae and pterygia can sometimes look similar to more serious eye growths, it is important for people to have them checked by an eye care professional.
* Usually, no treatment is needed.
* Artificial tears can be used to relieve the sensation of a foreign body in the eye and to protect against dryness.
* Surgery to remove the pinguecula or pterygium is advisable when the effect on the cornea causes visual defects or when the thickening is causing excessive and recurrent discomfort or inflammation.
* Sometimes surgical removal is also performed for cosmetic reasons. However, healing from this type of surgery, although usually painless, takes many weeks, and there is a high rate of recurrence (as high as 50-60% in some regions).
* Surgery is avoided unless problems due to the pinguecula or pterygium are significant.
Beta radiation- slows regrowth of pingueculae and pterygia, but can cause cataracts.
A preferable method is the topical application of the anticancer drug, mitomycin-C.
Most pingueculae and pterygia grow slowly and almost never cause significant damage, so the prognosis is excellent. Again, a diagnosis must be made to rule out other more serious disorders.
Pingueculae and pterygia have been linked to exposure to UV radiation, so UV exposure should be reduced. Sunglasses should block 99-100% of UV-A and UV-B rays. Patients should speak to their eye care professionals about protective coatings on sunglasses or regular spectacles. Protecting the eyes from sunlight, dust, and other environmental irritants is a good idea.
Iris Melanoma
Tumors can grow within and behind the iris.
Many iris tumors are cysts or nevi, malignant melanomas can occur in this area. It is important to have slit-lamp photographs of your iris tumor. These pictures can establish a baseline for future comparisons.
High frequency ultrasound is the only way to see how deep an iris tumor extends within and through the iris. Ophthalmic oncologists use high frequency ultrasound to diagnose and follow iris tumors for evidence of growth. Characteristics which suggest that an iris tumor is cancerous include seeing blood vessels within the tumor, evidence that the pupil is deformed, and the development of a cataract beneath the tumor.
Tapioca-colored iris tumor has pulled the iris pigment epithelium out onto the surface of the iris stroma.
The most important finding is documented growth. Since iris melanomas are commonly small, and rarely (1-5%) spread to other parts of the body, these tumors are usually watched for evidence of growth before treatment is considered.
Treatment:
Most pigmented iris tumors do not grow. They are photographed and monitored with periodic observation. When an iris melanoma is documented to grow, we know that it can damage the eye (usually cause glaucoma). Then, treatment (despite its risks) becomes more reasonable.
Small melanomas: Most small iris melanomas can be surgically removed.
Medium-sized melanomas: Large iris resections are possible, but plaque radiotherapy may be considered for these tumors. A cataract is likely to develop, but since the radiation plaque is far from the central retina, vision limiting radiation retinopathy is unlikely.
Large-sized melanomas: These cases can be difficult to treat with eye-sparing therapies. Many of these tumors cause untreatable glaucoma and may require removal of the eye.
Squamous cell carcinoma
A cancer that develops from squamous cells found in the skin that covers the outside and lines the inside of the body
* Second most common malignant eyelid neoplasm in the United States, after basal cell carcinoma.
* Most often encountered in elderly, fair-skinned individuals who have a history of chronic sun exposure.
* Patients presenting with this lesion may demonstrate a roughened scaly patch of tissue on or near the lid margin or in the canthal region. The area is typically red, elevated and nodular, with crusted and/or bloody margins. Often, patients describe this lesion as "a non-healing scab."
Squamous cell carcinoma in its early stages is easily confused with a multitude of other eyelid lesions, both malignant and benign. Some of these lesions include:
* basal cell carcinoma
* sebaceous gland carcinoma
* follicular kurtosis
* actinic kurtosis
* seborrheic keratosis, and
* keratoacanthoma.
Patients are mostly asymptomatic, displaying only mild irritation. Acuity is not affected unless the lesion is so large as to obscure the visual axis.
Squamous cell carcinoma is a potentially invasive tumor derived from surface epithelium. In the early stages, the normal epithelial cells are replaced by atypical squamous cells throughout the epidermis, resulting in a loss of normal maturation. This stage is sometimes referred to as squamous cell carcinoma in situ. After the dysplastic squamous cells encroach beyond the borders of the basement membrane, the lesion is referred to as invasive squamous cell carcinoma.
UV radiation is a substantial risk factor and demonstrates a distinct association with this disease. This is supported by the fact that the majority of squamous cell tumors arise on the lower lid margin and medial canthus, the two periocular areas most susceptible to sunlight exposure. Increasing age and northern European descent are two other commonly associated factors in patients with squamous cell carcinoma.
Lesions may be treated with:
. Surgical excision
2. Radiation therapy
3. Chemotherapy, or
4. Cryotherapy.
Preferred course for most cases is surgery, with broad margins to ensure complete removal. Frozen tissue sections of the tumor borders are evaluated intraoperatively to further assure that the lesion is excised completely (Mohs micrographic technique). This method offers the greatest success with the least incidence of recurrence. Local radiation and/or systemic chemotherapy may be used in managing squamous cell carcinoma when surgery is intolerable or refused by the patient. Both of these modalities carry significant side effects, and neither is as efficacious as surgical intervention. Cryotherapy has been used somewhat effectively for smaller tumors, but does not ensure complete tumor eradication, and therefore results in a high recurrence.
* Squamous cell carcinoma represents approximately 5 percent of all eyelid malignancies.
* While this particular neoplasm does possess the ability to invade local tissues and metastasize to other organ systems, it is not a particularly aggressive tumor.
* Its rate of development is quite slow, and metastasis is exceedingly rare. Still, the potential for damage exists in cases where diagnosis and treatment are delayed.
* Early biopsy is often the key to diagnosis. Suspicious lid lesions, which demonstrate irregular growth, changes in color or appearance, or discharge of a purulent or bloody nature should be biopsied to rule out cancerous entities. Confirmed malignancies should be referred promptly for treatment by an oculoplastics specialist or, where possible, an ocular oncologist.
Early onset cataract
Sunlight consists of ultraviolet (referred to as UVA or UVB) radiation, which penetrates the layers of the skin. Both have destructive properties that can promote cataracts. The eyes are protected from the sun by eyelids and the structure of the face (overhanging brows, prominent cheekbones, and the nose). Long-term exposure to sunlight, however, can overcome these defenses.
* UVB radiation produces the shorter wavelength, and primarily affects the outer skin layers. It is the primary cause of sunburn. It is also the UV radiation primarily responsible for cataracts. Long-term exposure to even low levels of UVB radiation can eventually cause changes in the lens, including pigment changes, which contribute to cataract development. (UVB also appears to be responsible for macular degeneration, an aging-related disorder of the retina.)
* UVA radiation is composed of longer wavelengths. They penetrate more deeply and efficiently into the inner skin layers and are responsible for tanning. The main damaging effect of UVA appears to be the promotion of the release of oxidants.
Basal Cell carcinoma
Most common malignancy of the eyelid, accounting for over 90% of all cancerous lid lesions.
Often, this tumor is discovered during routine slit lamp evaluation.
Usually no associated pain or discomfort.
More common in older, fair-skinned individuals, especially with a history of prolonged or excessive exposure to sunlight.
The lower lid margin and medial canthus are the most common areas involved.
The basal cell lesion presents in one of three ways:
. The nodular form appears as a small, translucent, raised area with poorly defined edges, and is firm to the touch;
2. The classic ulcerative presentation is a nodular lesion that over time has developed telangiectasia (a reddish hue caused by persistent, and virtually permanent, dilation of capillaries) along the surface and an atrophied inner portion, creating a "pearly," indurated outer margin with an excavated center; and
3. Less frequently, the sclerosing or morpheaform basal cell carcinoma form, which has a firm, pale, waxy yellow plaque with indistinct borders.
There is no single known cause for all forms.
There is a distinct association with increasing age and exposure to UV radiation.
Caucasians have a much greater chance of developing basal cell carcinoma than other races.
Progression of this tumor is, in most cases, exceedingly slow.
Left untreated the lesion may in time invade deeper structures. Fortunately, metastasis is rare, and complete recovery is possible with proper therapy.
Basal cell carcinoma can be treated with
* surgical excision,
* radiation therapy or
* chemotherapy.
The preferred course for most cases is surgery, with broad margins to ensure complete removal. Local radiation therapy and/or systemic chemotherapy can manage basal cell carcinoma when surgery is intolerable or refused by the patient. Both of these modalities carry significant side effects, however, and neither is as effective as surgical intervention.
* Basal cell carcinoma is rarely life-threatening because of its non-metastatic, slow-growing nature. However, this tumor does possess the capacity, over time, to cause significant local destruction, and must always be treated appropriately.
* Early biopsy is often the key to diagnosis. Biopsy all suspicious lid lesions which demonstrate irregular growth, changes in color or appearance, or purulent or bloody discharge to rule out cancer. You should refer confirmed malignancies promptly to an oculoplastics specialist or, if possible, an ocular oncologist.
