The freshness in the eyes (or medically, a pterygium) is a high and superficial external ocular mass that generally forms on the perilimbal conjunctiva and extends to the corneal surface. The pterygium may develop in the nasal and temporal limbus and affect one or both eyes.
Pterygium can range from small quiescent atrophic lesions to large, aggressive, fast-growing fibrovascular lesions that can distort corneal topography and, in advanced cases, can obscure the optical center of the cornea.
The pathophysiology of the pterygium is characterized by the elastotic degeneration of collagen and fibrovascular proliferation, with an overlying cover of the epithelium. The histopathology of abnormal collagen in elastotic regression shows basophilia with staining with hematoxylin and eosin.
This fabric is also stained with elastic stains, but it is not an actual stretchy fabric since it is not digested by elastase.
The incidence of pterygium within the United States varies according to geographic location. Within the continental United States, prevalence rates range from less than 2% above the 40th parallel to 5-15% in latitudes between 28-36 °.
It is believed that there is a relationship between increased prevalence and high levels of exposure to ultraviolet light at lower latitudes.
At the international level, the relationship between the decrease in incidence at high latitudes and the relatively higher incidence at lower latitudes persists.
A pterygium can cause a significant alteration in visual function in advanced cases. It can become inflamed, which causes redness and eye irritation.
It is reported that pterygium occurs in men twice as often as in women.
It is uncommon for patients to present with pterygium before age 20. Patients older than 40 years have the highest prevalence of pterygium, while patients of 20-40 years have the highest incidence of pterygium.
The visual and cosmetic prognosis after pterygium excision is good. The procedures are well tolerated by patients, and, in addition to some discomfort in the first postoperative days, most patients can resume their total activity within 48 hours after surgery.
Those patients who develop recurrent pterygium can be removed with repeat surgical excision and graft, with conjunctival / limbus autografts or amniotic membrane transplants in selected patients.
Patients with pterygium should reduce exposure to ultraviolet light whenever possible. The methods to reduce exposure to ultraviolet rays include sunglasses with ultraviolet blocking, a wide-brimmed cap, and the search for protection against direct sunlight.
Patients at high risk of developing pterygium due to a positive family history of pterygium or prolonged exposure to ultraviolet radiation should be educated in the use of ultraviolet blocking lenses and other means to reduce ocular exposure to ultraviolet light.
Clinical presentation of the pterygium
Patients with pterygium have various ailments, ranging from no symptoms to significant redness, swelling, itching, irritation, and blurred vision associated with raised lesions of the conjunctiva and the contiguous cornea in one or both eyes.
A pterygium can present as any of a range of fibrovascular changes on the surface of the conjunctiva and the cornea. It is more common for the pterygium to be present in the nasal conjunctiva and extend to the nasal cornea. However, it may occur temporarily, as well as in other places.
The clinical presentation can be divided into two general categories:
- A group of patients with pterygium can present a minimal proliferation and a relatively atrophic appearance. Pterygiums in this group tend to be flatter and slow-growing and have a relatively lower incidence of recurrence after excision.
- The second group presents a history of rapid growth and a significant elevated fibrovascular component. The pterygium in this group has a more aggressive clinical course and a higher recurrence rate after excision.
Risk factors for pterygium include (1) increased exposure to ultraviolet light, which includes living in subtropical and tropical climates, and (2) participating in occupations that require outdoor activities.
A genetic predisposition for the development of pterygia seems to exist in certain families.
There is a preference for men to develop this condition significantly higher than for women. However, this finding may represent a greater exposure to ultraviolet light in this part of the population.
Complications of pterygium include the following:
- Distortion and reduction of central vision
- Chronic healing of the conjunctiva and the cornea
The extensive involvement of the extraocular muscles can restrict ocular motility and contribute to diplopia. In patients who have not yet undergone surgical excision, the medial rectus muscle scarring is the most common cause of diplopia.
In patients with pterygium who have previously undergone surgical excision, scarring or disinsertion of the medial rectus muscle is the most common cause of diplopia.
In patients with significantly elevated pterygia, focal drying and subsequent thinning of the adjacent cornea rarely occurs.
Postoperative complications of pterygium repair may include the following:
- Reaction to suture material
- Dehiscence of the conjunctival graft
- Corneal scars
- Perforation of the eyeball, vitreous hemorrhage, or retinal detachment (all rare)
Late postoperative complications of pterygium beta radiation may include scleral and corneal thinning or ectasia, which may occur years or decades after treatment. Some of these cases can be pretty difficult to manage.
In some cases, it has been reported that the complementary use of topical MMC in and after pterygium surgery causes a similar ectasia or fusion of the sclera and the cornea.
The most common complication of pterygium surgery is postoperative recurrence. Simple surgical excision has an approximately 50-80% high recurrence rate. The recurrence rate has been reduced to about 5-15% using conjunctival / limbus autografts or amniotic membrane transplants at the time of excision.
Rarely, malignant degeneration of the epithelial tissue that covers an existing pterygium may occur.
Differential diagnostics of the pterygium
Consider the possibility of pseudopterigión (chemical or thermal burn, trauma, marginal corneal disease) in the differential diagnosis.
Consider neoplasms (e.g., carcinoma in situ, squamous cell carcinoma, other neoplastic diseases) in the differential diagnosis.
Pingueculas (i.e., actinic lesions confined to the perilimbal conjunctiva that do not extend to the cornea) should also be considered in the differential diagnosis. [sixteen]
Pingueculae are standard, usually small, asymptomatic (often yellow) nodules that appear on the bulbar surface of the conjunctiva. They are most commonly found on the nasal side but may also occur in the temporal conjunctiva or the nasal and temporal conjunctiva in the eyes of some patients.
It is believed that pingueculas are associated with exposure to actin (sunlight) in susceptible individuals.
Pingueculae occasionally may be subject to some inflammation with symptoms of itching, burning, or mild pain. In the absence of inflammation or significant cosmetic complaints, pingueculae are generally ignored (both by the patient and the doctor). They can be treated with artificial tears if they are mildly symptomatic, like pterygium.
Rarely are anti-inflammatory eye drops may be required. On even more infrequent occasions, surgical excision may be beneficial in treating pinguelecles.
Histopathologically, the pinguelecles show mild to moderate focal thickening of the conjunctival stroma with elastotic collagen degeneration.
Squamous cell carcinoma, conjunctival
The corneal topography can be very useful in determining the degree of irregular astigmatism induced by an advanced pterygium.
External photography can help the ophthalmologist follow the progression of the pterygium.
Multiple different procedures have been advocated in the treatment of pterygium. These procedures range from simple excision to sliding flaps of the conjunctiva with and without adjuvant external beta-radiotherapy and topical chemotherapeutic agents, such as mitomycin C (MMC).
The use of free conjunctival grafts (with or without limbal tissue) at the same time as primary excision of the lesion has been widely advocated as the preferred treatment modality for aggressive pterygia. For moderate to severe pterygia, some corneal surgeons use amniotic membrane transplants.
Both conjunctival autografts and amniotic membrane transplants can be sutured in the adjacent conjunctiva and the underlying cornea. Some corneal surgeons seal the graft tissue over the underlying sclera with the help of fibrin glue instead of sutures.
A study by Kheirkhah et al. found that conjunctival inflammation was much more familiar with amniotic membrane transplantation than with conjunctival autografts after pterygium surgery. However, with the control of said inflammation and the intraoperative application of mitomycin C, both techniques produced similar final results.
Treatment and management of the pterygium
Patients with pterygium can be observed unless the lesions show growth towards the center of the cornea or the patient shows symptoms of redness, discomfort, or alterations in visual function. The pterygium can be removed for aesthetic reasons, as well as functional abnormalities of vision or pain.}
Surgery for a pterygium excision is usually performed in an outpatient setting under local or topical anesthesia with sedation, if necessary.
A prospective, randomized, interventional study by Kheirkhah et al. evaluated 56 patients who underwent pterygium excision with MMC and an amniotic graft. Of these 56 patients, 28 received MMC in the perilimbal bare sclera for 1-5 minutes, while 28 other patients received MMC under the conjunctiva.
Endothelial cell studies revealed a 3.4% loss of cells in the naked sclera group compared to 4.8% in the subconjunctival group at six months. No complications were observed in any group; however, the study was small.
A prospective nonrandomized study by Bahar et al. examined the risk of endothelial cell loss in 43 subjects after pterygium surgery with MMC and conjunctival autograft. The study included a control group with a primary pterygium excision without MMC.
Although the number of patients in each group was small, patients who received MMC experienced a 4% reduction in endothelial cells at three months, compared with no loss in the control group. This suggests that MMC can affect the endothelial cell count in patients undergoing pterygium excision.
Despite the relatively small sample sizes, both studies reported statistically significant decreases in corneal endothelial cell counts (P values ≤ 0.05) up to 3 months after surgery.
The authors point out that MMC placement in the limbus can be a risk factor for scleral melting. Therefore, the authors advise the placement of MMC only in the area of fibrovascular conjunctival tissue.
Hirst initiated a nonrandomized prospective study of the evolution of previous pterygium surgical techniques that included extensive destruction of the overlying conjunctiva and the underlying Tenon’s fascia in the vicinity of the pterygium, combined with a large autograft that retained the limb harvested from the surface superior conjunctival.
Hirst subsequently published his results in the longer term after more than 1000 surgeries, including 806 primary pterygia and 194 recurrent pterygiums. The author had more than one-year follow-up in 99% of these patients, with a mean follow-up of 616 days.
The author reported only one recurrence among those 1000 patients, significantly less than previously reported for primary and secondary pterygium surgeries.
This technique did not require antimetabolites and avoided limbal stem cells at the conjunctival autograft collection site. In addition to a reduction in expected recurrences, Hirst also reported a lower rate of postoperative complications with less than expected postoperative granulomas and conjunctival inclusion cysts less than expected.
In the postoperative period, the eye is usually patched during the night, and it is subsequently treated with topical antibiotics and anti-inflammatory drops and ointments.
Theoretically, minimizing exposure to ultraviolet radiation should reduce the risk of pterygium development in susceptible individuals. Patients are advised to wear a hat or cap with a rim, as well as coatings that block ultraviolet light on the lenses of sunglasses/sunglasses for use in sun exposure areas.
This precaution is even more critical for patients who live in tropical or subtropical areas or for those patients who perform outdoor activities with a high risk of exposure to ultraviolet rays (for example, fishing, skiing, gardening, and construction jobs). Fresh air).
Additional outpatient care
In the postoperative period, topical steroids are gradually reduced after pterygium excision. It is necessary to observe patients with topical steroids to reduce the risk of related problems, such as elevated intraocular pressure and cataracts.