Optometrists Find High Incidence of Eye Growths and Bumps on White of Eyes in Northern Colorado are Benign & Often Pinguecula

A large number of people in the Fort Collins show up at the optometrists office with benign growths on the white part of their eye referred to as pingueculas. Actually they develop on the conjunctiva, the clear tissue that covers the white part of the eye (the sclera). Often they appear as mildly elevated yellowish bumps, visible to the patient or a family member with a urgent rush to the eye doctor. Often people are reluctant to discuss their concerns hoping it will be found during an eye exam. You should not hesitate to mention this at the beginning of you visit to the optometrists office. Because they are so common, you eye doctor may not mention the presence of a pinguecula on your eye unless you ask. While most optometrists find pingueculas developing in patients eyes who are over the age of 40, it is becoming more common to see them by the mid twenties. They are presumed to be caused by a UV radiation from the sun and low level irritants like dust and small particles in the wind. The incidence increases closer to the equator. Fort Collins East of I-25 they are extremely common due to the farming industry with people spending larger amounts of time outdoors and in dusty environments. People who spend their leisure time on motorcycles are also more at risk due to the ultraviolet exposure and particles from the blowing wind.

What Causes Eye Growths of Pingucula

Just as skin loses is capacity to stretch with age, so does the conjunctival tissue when it is exposed to sunlight and irritation over a cumulative period of years. In Northern Colorado people frequently visit doctors for skin changes that are essentially occurring from the the same as the eye conjuntival changes.

Eye Doctors have found the elastosis, or the capacity of the tissue to smoothly stretch and return to normal is compromised from changes to the conjunctival tissue. Collagen forms the framework, but elastin protein fibers around the collagen fibers provide the stretching capacity. The UV radiation in Fort Collins is higher due to the altitude, reflections from snow, and the amount of time we spend outdoors. With close to 300 days a year of sunshine the UV exposure is higher than most areas at a similar latitude. Altitude increases the UV dosage by 4-5% /1000 feet of elevation gain. Compared to sea level this adds approximately 25% above sea level exposures.

First there is an accumulation of abnormal cells that are altered elastin and / or collagen.  Eventually the area starts to lose cells and becomes more of a deposit of protein materials often referred to as hyaline deposits. Calcification can occur over time also. Several theories have been proposed by eye research clinics for the changes seen in the tissues that form the pinguecula.  This UV radiation and low level chronic irritation causes changes that may be:

1. An increase in the production of elastin fibers by the fibroblast cells and changes to the elastin nature into a more twisted form as they replace some of the collagen fibers. This may induce degenerative changes to the collagen fibers.
2. A interference with the natural cycle of cell programmed cell death of elastin resulting in an overproduction that takes on the abnormalities.
3. A degradation of the collagen fibers into a compromised form resembling elastin.
4. A combination of the above

Other factors may make the conjunctival tissue more susceptible to forming pinguecula.

1. Since the conjunctiva tissue does not have the tough keratin layer like the skin it is damaged faster by UV radiation.
2. The clear conjunctiva tissue is also transparent and the solar radiation that is not absorbed passes through to the sclera. We know from science that color of the surface being irradiated has a large bearing on the amount of back reflected radiation including UV.[1]   It is a very thin tissue, and the white scleral tissue underneath it with it’s white coloration should have an albedo in the range of 80-90% similar to the reflectance of snow. Measured animal studies of conjunctival tissue reflectivity across the 440 to 1000+nm range shows a steady reflectance of above 40%. Somewhere between 40 to 80 percent of the UV radiation is being added to the initial dose as it passes through. This extra back reflection of UV into the conjunctiva tissue also increases the exposure and ages the tissue faster than skin.
3. Eye conditions that increase the size of the fissure, or how wide your eye stays open, also will increase the incidence of pinguecula. Thyroid eye disease and eyes that are not as deeply recessed (the beady eyed individual with a protruding eyebrow to shadow the eye) or more likely to develop pinguecula. Studies have shown an increase in pinguecula in patients with Thyroid Orbitopathy (hyperthyroid or an overactive thyroid gland that effects the eye) that is only significant with the widened eye fissure or amount of the eye normally exposed when open). Increased dry eyes was not correlated further suggesting UV exposure as a causative factor. [5]
4. The nose acts to reflect more light onto the eye somewhat like a dull mirror, and pinguecula are more commonly found on the white side closest to the eyes, but they are also found on the temporal side.
5. The deeper, or basal layers of the superior nasal conjunctival tissue contain more dendritic cells. Dendritic cells are a type of antigen-presenting cell (APC). Antigens are molecules or molecular fragments that bind to a site on on the surface of cells, and except for autoimmune diseases they are the molecules from outside the body. Dendritic cells present them to the T helper cells that increase the immune response and that cause an increase in inflammatory cells. The tears flow towards the nose by slight eyelid horizontal movements that accompany each blink. This ensures a continuous flushing of debris and antigens from the tear film, Since the tears flow in this direction logically their would be more dendritic cells to help remove the excess antigens. Due to the density of the dendritic cells and the propensity to create more inflammation, it has been postulated this may increase the overall likelihood of pinguecula forming in the nasal region.
6. Psoralen plus ultraviolet A (PUVA) treatment has been used widely in the past for various dermatoligic conditions. It has seen a reduction in use due to other methods. PUVA uses a photosensitizing agent (8-methoxypsoralen, Oxsoralen®) taken orally or applied to the effected area before exposure to ultraviolet A  light (320-400 nm).  At least one case of pinguecula associated with PUVA has been reported. (the patient was in poor in compliance with eye protection)

Pinguecula Are Always Benign Growths

Once a Pingueclua has been properly diagnosed by your optometrist you can rest assured. Pinguecula are always benign growths and never develop into any form of eye cancer. They can start to grow across the clear cornea tissue on the front of the eye at which point they are referred to as pterygium. Pterygium need to be followed as they need to be removed by an eye surgeon if they approach to close to the line of sight. While the surgical removal is fairly simple, they tend to recur and leave a scar. That leaves a wait and follow choice by your eye doctor. Because they are so slow to develop it is fairly easy to manage. New technology is reducing the recurrence, but remember, the majority of pingueculas don’t develop into pterygiums. In our Fort Collins Eye Clinic we occasionally see patients with symptoms related to pinguecula.

Pinguecula Symptoms and Signs

The elevation may disrupt the normal tear resurfacing on the eye and create an area of dryness and discomfort. It can also result in the edges of soft contact lenses settling poorly on the eye and leaving a gap between the soft contact lens and the conjunctiva. This often results in the lens drying out and the peripheral contact lens edge curling away from the conjunctiva.  Contact lens patients will blink and subsequently the eyelid movement can eject the contact lens. Rigid gas permeable lenses may leave a gap over the conjunctiva and edges of the cornea that dies out and damages the peripheral cornea epithelium surface cells and the conjunctival cells. The edge of the gas permeable lens may also irritate the pinguecula and result in a chronic red eye when contact lenses are worn. This can often be resolved by changing the diameter or size of the gas permeable contact lens.   A test used in research facilities called “tear ferning” evaluates the mucous layer of tears by allowing a  sample to dry on a slide and crystallize. This is often abnormal around pinguecula indicating a mucous irregularity inducing dry eyes. Occasionally pinguecula become inflamed and need prescription eyedrops to restore comfort. The incidence of problems is low and treatable so eye doctors almost never remove a pinguecula.

Optometrists Prevetative Steps For Pinguecula

UV prescription eyeglasses (or non prescription quality sunwear) is the most important preventive step you can take.  Not only will it help prevent pinguecula, but also a number of other eye diseases associated with sunlight exposure. Do a favor for your children and teenagers eye health, start them in prescription sunglasses (transition lenses that lighten and darken also offer UV protection). When you think of sunscreen think of sunscreen for the eyes. The more time you spend in the sun, the more you should think of sunwear that wraps around your face and protects the sides. Up to 40% of the UV exposure can still enter from the unprotected side of a normal pair of eye glasses. Special motorcycle eyeglass frames have become very popular in our Ft Collins Eye Care Center due to the side protection from UV and wind & dust. Wearing a hat with a brow helps reduce UV exposure. Limiting midday sun exposure is very useful when possible. The morning and afternoon sun is lower on the horizon and has a much longer path to travel through the atmosphere which filters out more UV. Don’t avoid the sun totally. While there is much controversy at this point, it does appear that some sun exposure is good for your health, reducing some forms of cancer and possibly decreasing the incidence of multiple sclerosis. While vitamin D may be the protective factor some studies indicate their may be other factors and biochemical involved.  Keep your eyes posted for more eye updates as we learn more about the fascinating world of vision!

References

[1] http://geography.about.com/od/physicalgeography/a/solarradiation.htm

[2} http://www3.interscience.wiley.com/journal/112130369/abstract?CRETRY=1&SRETRY=0

[3] Hoang-Xuan,Thanh;  Baudouin, Christophe     Inflammatory Diseases of the Conjunctiva,  Catherine Creuzot-Garcher

[4] Journal of the American Academy of Dermatology
Volume 57, Issue 1, Pages 177-178 (July 2007)
Pinguecula following psoralen and ultraviolet A therapy
Amit Garg, Michael Loosemore, BAb

[5] Cornea:
June 2010 – Volume 29 – Issue 6 – pp 659-663
doi: 10.1097/ICO.0b013e3181c296ab
Clinical Science
Prevalence of Pinguecula and Pterygium in Patients With Thyroid Orbitopathy
Ozer, Pnar Altiaylik MD; Altiparmak, Ugur E MD; Yalniz, Zuleyha MD; Kasim, Remzi MD; Duman, Sunay MD