Mohamed Baana
Definition
Pinguecula is a benign elevated lesion (yellowish-white) of the bulbar conjunctiva that is usually situated on the nasal or temporal side and close to the limbus. It is a degenerative disease that has elastotic degeneration of the conjunctival stroma and is clinically and pathologically distinct from pterygium, which extends across the limbus to the cornea, usually bilateral and located interpalpebral (1).
Causes and Risk Factors
Pinguecula is mostly caused by chronic exposure to ultraviolet (UV) radiation, mainly UVB, which causes solar elastosis in the subepithelial collagen of the conjunctiva, which is directly associated with actinic damage. (1, 2) Long-term exposure to dust, wind, and dry weather only intensifies the stress of the conjunctiva, which facilitates the development of lesions (3).
Old age is an established risk factor, with the incidence rising gradually after the 4th decade (1). Male gender and outdoor occupational activity are also among the major risk factors, which can be attributed to the higher cumulative UV exposure (4). Mechanical friction, tear film damage, and chronic hypoxia under lenses are contributing factors to the development and progression of pinguecula (5). One particular occupational risk is associated with exposure to high temperatures (tandoor ovens), where infrared radiation and heat in the presence of UV exposure are a major cause of pinguecula development and progression in the workers (6).
Epidemiology
The population-based studies give crucial information on the world burden of pinguecula. A study conducted in Tehran, Iran, with 4,408 participants with a median age of 40 years and older found a pinguecula prevalence of 20.2% (22.8% prevalence in men and 18.0% prevalence in women), with age-related associations (odds ratio rising with years of service), male sex, and residence study area (pinguecula was more prevalent in rural areas than in urban areas). (4) Pinguecula was found in 68.4% of the exposed workers in an occupational environment with extreme temperatures of heat and UV radiation (hospital kitchen workers using tandoor ovens) versus 31.6% controls, demonstrating the dose-dependence of thermal-UV synergy. (6)
The patients who wear contact lenses are a unique high-risk group. These epidemiological trends highlight the etiological multifactor involving actinic, mechanical, and thermal stressors in relation to long-term use of soft contact lenses that causes pinguecula in 59.3% of the participants with long-term contact lenses and 29.5% of non-contact lens users (5).
Pathophysiology
Pinguecula is characterized by a pathophysiological hallmark, which is the loss of collagen in the conjunctivae substantia propria by elastotic degeneration. Hyaline plaques, fragmented elastic fibres with basophilic staining, and some calcifications are observed under the microscope due to oxidative stress and free radical damage on the extracellular matrix components by UV rays (1).
On a molecular level, transcriptome profiling of tissue in pinguecula reveals that the condition displays strong expression of inflammatory (e.g., IL-6, TNF-α), fibrotic (TGF-β pathway), and DNA repair-defective genes, which are indicative of genomic instability (7). Transcriptome profiling of pinguecula tissue has more genes clustering around the chronic inflammation and UV response pathways, which explains its non-invasive nature (7).
Staging/Classifications
Even though there is no generally accepted staging system of pinguecula, it is classified on the basis of its morphological features. In cases related to contact lenses, the lesions are graded in terms of size (small < 2 mm, moderate 2-4 mm, large > 4 mm), elevation (flat, mildly elevated, highly elevated), and vascularity (avascular, mildly vascular, highly vascular) (1). There is a standardized grading scale (0-3): Grade 0 (none), Grade 1 (barely visible), Grade 2 (definite elevation), Grade 3 (prominent with corneal encroachment risk). (5)
Improved imaging increases the accuracy of classification. Fundus autofluorescence demonstrates a high level of hyperautofluorescence in pinguecula, which is associated with the presence of accumulation of elastotic material, and could help distinguish it between pinguecula and pterygium or conjunctival neoplasia. (8).
Signs and Symptoms
Pinguecula is clinically presented as a triangular, yellowish, interpalpebral conjunctival elevation, most commonly nasal (85-90% of cases) (1,3). Surface is smooth or mildly rugose, sometimes including dellen formation caused by the tear film destruction. (1)
Symptoms of the pingueculae are usually mild or absent, and they are discovered by chance during examination (9). They can be more serious in contact lens wearers with lens intolerance and frequent inflammation (5). Autofluorescence imaging of the hyperautofluorescent nature is a characteristic sign of the pingueculae, even in the asymptomatic cases (8).
Management
Most pingueculae do not need treatment and are treated with expectancy and patient education regarding UV protection (1). Artificial tears and lubricating ointments can be used as the first-line treatment of the symptomatic pingueculae, although long-term use is discouraged because of steroid-related complications (1,10). Short courses of topical corticosteroids (e.g., fluorometholone 0.1%) can be used to treat the symptomatic pingueculae, but the long-term use is avoided due to the steroid-related complications (1).
In cases of pinguecula-induced refractoriness to medical treatment, dry eye, argon laser photocoagulation provides an alternative, minimally invasive treatment. Case reports record full recovery of symptoms and flattening of lesions in 3 months after surgery, facilitating increased tear breakup time and Schirmer values (10). The procedure is aimed at elastotic tissue, whereby there is a controlled thermal coagulation and occurrence of fibrosis.
Simple excision has a high recurrence rate (as high as 50%), with higher success rates augmented with amniotic membrane transplantation or mitomycin-C (1).
Complications
Although it is benign, a pinguecula may cause serious morbidity in people prone. Constant surface irritation can trigger repeated epithelial fissure or dellen (1) in contact lens wearers; there is progressive growth that disrupts lens fit, deposition, and giant papillary conjunctivitis risk (5).
Pingueculitis, inflammation of the lesion, is associated with inoculation of pain, redness, and swelling, which is usually spurred by environmental indignities or overwear of contact lenses (1). The Molecular evidence of genomic instability, such as p53 mutations and DNA repair defects, raises the theoretical risk of malignant progression, although the clinical progression to squamous cell carcinoma is extremely uncommon (7)
Although subjective, cosmetic effect may bring about psychological discomfort, especially large or bilateral lesions (9). Occupational ramifications are significant, especially in careers that need contact lenses or prolonged exposure to the outside (4,6).
References
- Somnath A, Tripathy K. Pinguecula. In: StatPearls. StatPearls Publishing, Treasure Island (FL); 2025. PMID: 32644391. https://www.ncbi.nlm.nih.gov/books/NBK558965
- Arenas E, Armas G, Ramirez A. Pinguecula. The Pan-American Journal of Ophthalmology. 2019 Jan 1;1. https://journals.lww.com/pajo/fulltext/2019/00000/pinguecula.2.aspx
- Beheshtnejad AH, Ghassemi H, Abdolkhalegh H, Atighehchian M. Clinical and autofluorescence findings in eyes with pinguecula and pterygium. Journal of Ophthalmic & Vision Research. 2023 Jul 28;18(3):260. https://doi.org/10.18502/jovr.v18i3.13773
- Fotouhi A, Hashemi H, Khabazkhoob M, Mohammad K. Prevalence and risk factors of pterygium and pinguecula: the Tehran Eye Study. Eye. 2009 May;23(5):1125-9. https://doi.org/10.1038/eye.2008.200
- Gul A, Goker H, Sabanci S, Kurt A, Turkyilmaz K. Relationship between pinguecula formation and exposure to tandoor ovens in a hospital-based study. International Journal of Ophthalmology. 2014 Dec 18;7(6):1014. https://doi.org/10.3980/j.issn.2222-3959.2014.06.19
- Mimura T, Usui T, Mori M, Yamamoto H, Obata H, Yamagami S, Funatsu H, Noma H, Honda N, Amano S. Pinguecula and contact lenses. Eye. 2010 Nov;24(11):1685-91. https://doi.org/10.1038/eye.2010.120
- Napoli PE, Sanna R, Iovino C, Fossarello M. Resolution of pinguecula-related dry eye disease after argon laser photocoagulation. International Medical Case Reports Journal. 2017 Jul 24:247-50. https://doi.org/10.2147/IMCRJ.S138786
- Suarez MF, Echenique J, López JM, Medina E, Irós M, Serra HM, Fini ME. Transcriptome analysis of pterygium and pinguecula reveals evidence of genomic instability associated with chronic inflammation. International journal of molecular sciences. 2021 Nov 8;22(21):12090. https://doi.org/10.3390/ijms222112090
- Sugar S, Kobernick S. The pinguecula. American Journal of Ophthalmology. 1959 Mar 1;47(3):341-5. https://doi.org/10.1016/S0002-9394(14)76535-3
- Bell A. Pinguecula. Journal of Visual Communication in Medicine. 2006 Jan 1;29(2):82-3. https://doi.org/10.1080/01405110600834168