Overview of Conjunctival Conditions
The conjunctiva is the thin, transparent mucous membrane that lines the inner surface of the eyelids (palpebral conjunctiva) and covers the white of the eye (bulbar conjunctiva). Because it is exposed to the environment and sits in direct contact with contact lenses, it is susceptible to a variety of conditions. Recognizing these conditions is essential for contact lens practitioners, as some require lens modification or discontinuation.
Pinguecula
A pinguecula is a yellowish-white, slightly raised lesion on the bulbar conjunctiva, most commonly found on the nasal side near the limbus. It represents a degenerative change in the conjunctival collagen, with deposits of protein, fat, and calcium.
Key characteristics:
- Located on the conjunctiva only; it never extends onto the cornea
- More common on the nasal side due to greater UV exposure in that area
- Usually bilateral and increases in prevalence with age
- Generally benign and requires no treatment unless inflamed
- Strongly associated with chronic UV exposure, wind, and dust
When a pinguecula becomes inflamed (reddened and irritated), it is called pingueculitis. This may cause discomfort and can be managed with lubricating drops or short-term anti-inflammatory agents.
Pterygium
A pterygium is a triangular, wing-shaped growth of fibrovascular tissue that extends from the conjunctiva onto the cornea. This is the critical distinction from a pinguecula: a pterygium invades the corneal surface.
Key characteristics:
- Typically grows from the nasal side, advancing across the limbus onto the cornea
- Can induce significant astigmatism by pulling on the corneal surface as it grows
- If it advances far enough, it can obstruct the visual axis and directly impair vision
- Surgical removal may be necessary when it threatens the visual axis or causes significant astigmatism
- Recurrence after removal is common, particularly in younger patients and those with ongoing UV exposure
Giant Papillary Conjunctivitis (GPC)
Giant Papillary Conjunctivitis is an immune-mediated inflammatory condition characterized by the formation of large papillae (bumps greater than 0.3mm in diameter) on the superior tarsal conjunctiva (the tissue under the upper eyelid). It is one of the most important contact lens-related conditions to understand.
GPC develops from a combination of:
- Mechanical irritation from the lens edge rubbing against the tarsal conjunctiva during blinking
- Allergic response to protein deposits that accumulate on the lens surface over time
Symptoms and signs include:
- Increased mucus discharge, especially upon waking
- Itching, particularly after lens removal
- Lens intolerance and excessive lens movement
- Large, cobblestone-like papillae visible on the upper tarsal plate when the lid is everted
Papillae vs. Follicles
Distinguishing between papillae and follicles on the conjunctival surface is a fundamental clinical skill because they indicate different underlying causes.
Papillae
- Have a central vascular core (a blood vessel runs through each bump)
- Appear reddish due to the blood supply
- Give a cobblestone appearance when numerous
- Found in: allergic conjunctivitis, bacterial conjunctivitis, GPC, and mechanical irritation from contact lenses
- Think: Papillae = Pink/red (vascular)
Follicles
- Are avascular lymphoid aggregates (no central blood vessel)
- Appear pale, grayish-white, or translucent
- Described as looking like grains of rice or tapioca pearls
- Found in: viral conjunctivitis, chlamydial infections, toxic reactions to medications
- Think: Follicles = Fade/pale (avascular)
Other Conjunctival Findings
- Subconjunctival hemorrhage: A bright red patch on the bulbar conjunctiva caused by a broken blood vessel. Usually harmless and resolves without treatment in 1-2 weeks
- Conjunctival injection: Generalized redness from dilated blood vessels, seen in many inflammatory and infectious conditions
- Chemosis: Swelling (edema) of the conjunctiva, causing it to balloon outward. Can occur with severe allergic reactions or infection
- Concretions: Small, yellowish deposits within the conjunctival tissue. Usually asymptomatic unless they erode through the surface, causing a foreign body sensation
Key Takeaways
- Pinguecula: yellowish conjunctival lesion that never crosses onto the cornea
- Pterygium: fibrovascular growth that extends onto the cornea and can induce astigmatism
- Both pinguecula and pterygium are associated with UV exposure
- GPC is caused by mechanical irritation and protein deposits from contact lenses; presents with large papillae under the upper lid
- Papillae are vascular (red, cobblestone) and indicate allergic/bacterial causes
- Follicles are avascular (pale, translucent) and indicate viral/toxic causes