Many systemic illnesses first manifest themselves in the eye or affect the eye secondarily. Many orally and parenterally administered medications gain access to the eye through the tear fluid and can adhere to the contact lens surface, accumulate in the hydrophilic stroma of soft lenses, and interact with the polymers of which the lenses are composed.

Fever elevates not only the core temperature, but also the temperature of the anterior ocular segment. Two consequences of this are a need for an increased amount of tear fluid and an alteration of the conjunctival flora. The normal temperature in the cul-de-sac is 35.6 ± 0.2°C; a rise of as little as 1–2°C creates a favorable environment for the growth of Pseudomonas, which explains why contact lens wearers are much more likely to develop Pseudomonas conjunctivitis or keratitis when suffering from a febrile illness, such as the common cold. Respiratory diseases such as bronchitis or bronchial pneumonia raise the incidence of acanthamoebal, fungal, and pneumococcal corneal ulcers in contact lens wearers.

Immune compromise of various causes, including AIDS, leukemia, and antineoplastic chemotherapy, predisposes to ocular infection. It is thus critical that contact lenses are not worn in such situations. Contact-lens-related complications are also more frequent in the presence of systemic diseases affecting the quality and quantity of tears, including thyroid, parathyroid, and other metabolic disorders and renal failure. Florid hepatitis may necessitate discontinuation of contact lenses, as may pregnancy or nursing, in rare cases.

Any allergic predisposition may complicate the wearing of contact lenses. Patients who are allergic to synthetic materials in general usually cannot tolerate any type of contact lens material. Patients with ectopic dermatitis may rapidly develop blepharitis after contact lenses are inserted, while patients with allergic vasomotor rhinitis may develop allergic blepharoconjunctivitis or keratopathy. Those who suffer from hay fever can rarely wear their lenses comfortably at the critical times of year.

Many ocular diseases can complicate the wearing of contact lenses. The contact lenses themselves, as well as lens care products and wetting solutions, may evoke an allergic response. Ocular infections can become more severe in the presence of contact lenses or be spread by the contact lenses to critical areas of the cornea. It is unknown at present whether premalignant ocular lesions are more likely to transform into malignancy when contact lenses are worn, but unnecessary risks should not be taken; thus, any pigmented spots on the lids or conjunctiva should be noted and photographically documented before fitting, and followed up at regular intervals thereafter.

Acute infections of the lids, conjunctiva, and cornea complicate contact lens wear. Hordeolum and (more rarely) lid abscess necessitate temporary discontinuation of contact lenses, as the lenses might otherwise be a vector for the spread of pathogenic bacteria to the cornea.

Chalazion, in its early infectious phase, poses the same risk to the contact wearer as hordeolum and necessitates temporary discontinuation of contact lenses. In its inactive phase, after healing and encapsulation, it may still be a mechanical hindrance to contact lens wear.

Chronic blepharitis is a major problem. Of the many etiological forms of chronic blepharitis, allergic squamous blepharitis is the most likely to develop in contact lens wearers because of an allergy to the lenses or to lens care products. Regardless of treatment, such patients hardly ever tolerate their lenses well over the long term.

Chronic, recurrent lid edema of any cause interferes with the lie of the lens on the eye. Contact lens wearers with this problem complain of a foreign body sensation and generally cannot wear contact lenses over the long term.

The lie of the lens is also disturbed by ectropion or entropion, as well as by post-traumatic or postsurgical alterations of lid function. Scarring of the lid margin after trauma or infection, lid paresis, or malposition of the punctum can interfere with the flow of tears and thereby complicate contact lens wear. Patients with these problems usually have to stop wearing contact lenses soon after the initial fitting because of a pronounced foreign body sensation and frequent lens loss.

Eyelashes that point inward scrape the cornea and conjunctiva with each lid movement, irritating the anterior ocular segment. If a contact lens is worn, they push it back and forth over the cornea. This condition must be excluded or, if present, corrected before contact lenses are fitted.

Lid function and the lie of the contact lens can be adversely affected by any malignant or benign mass of the eyelid, such as a papilloma or sebaceous cyst. Before contact lenses are fitted, such masses should be excised.

Fig. 391 Hordeolum, upper lid.

Fig. 392 Ulcerated chalazion on the upper lid, infectious process.

Fig. 393 Herpes, upper lid margin.

Fig. 394 Herpes simplex, upper lid.

Fig. 395 Conjunctival cyst, tarsal conjunctiva of lower lid.

Fig. 396 Cyst, inner surface of lower lid.

Fig. 397 Internal chalazion, lower lid.

Fig. 398 Benign tumor of the lower lid margin.

Fig. 399 Lid margin papilloma, center of upper lid.

Fig. 400 Milium, inner canthus, lower lid.

Fig. 401 Wart, central upper lid margin.

Fig. 402 Entropion, lower lid.

Fig. 403 Ectropion, lower lid.

Acute or chronic conjunctivitis of any etiology absolutely contraindicates contact lens wear. Wearing contact lenses in this situation would not only create an intense foreign body sensation but would also be likely to exacerbate the disease process by provoking additional inflammation. Innumerable cases of corneal ulceration in contact lens wearers have occurred on the background of prior bacterial, fungal, or viral conjunctivitis. Conjunctival cuts, hemorrhages, edema, or lesions should be allowed to heal completely before lens wear is resumed.

Conjunctival growths, such as pingueculae or pigmented spots, often cause mechanical problems. It remains an unresolved question whether the mechanical irritation caused by a contact lens can promote the transformation of a pigmented spot to a malignant process (melanoma). It would seem prudent to remove any nevus that might be touched by a contact lens before the lens is fitted.

Fig. 404 Distichiasis, lash abrading the cornea, foreign body sensation.

Fig. 405 Dacryocystitis, occlusion of lacrimal pathway.

Fig. 406 Dacryocystitis, occlusion of lacrimal pathway.

Fig. 407 Chronic bacterial conjunctivitis.

Fig. 408 Pinguecula, conjunctival erosion from the edge of a hard contact lens, stained with rose bengal.

Fig. 409 Conjunctival phlyctena.

Fig. 410 Pseudopterygium from keratitis.

Fig. 411 Pseudopterygium from alkali burn.

Fig. 412 Pterygium.

Fig. 413 Conjunctival papilloma adjacent to the limbus.

Fig. 414 Conjunctival tumor adjacent to the limbus.

Fig. 415 Conjunctival tumor adjacent to the limbus.

Fig. 416 Conjnctival nevus, benign.

Fig. 417 Conjunctival nevus.

Fig. 418 Conjunctival nevus, vascularized.

Fig. 419 Conjunctival melanosis.

Fig. 420 Conjunctival melanoma.

Fig. 421 Conjunctival cyst after a perforation of the bulb, aphakia.

Fig. 422 Conjunctival cyst.

Fig. 423 Conjunctival cyst with extension to the retrobulbar space.

Fig. 424 Conjunctival cyst after perforation of the bulb.

Fig. 425 Prolapsed conjunctival fatty tissue.

Corneal infections and acute corneal processes of any other type contraindicate the wearing of contact lenses. All contact lenses impair the metabolism of the cornea to some extent; though the disturbance is well tolerated by a healthy eye when modern lens systems are used, it is likely to contribute to the progression of any corneal disease that may be present. Within a few hours of being covered by a contact lens, keratitis can develop into a corneal ulcer, and corneal herpes can develop into metaherpetic keratitis.

The situation is somewhat different in deformities or degenerative diseases of the cornea, which are often, in fact, a medical indication for contact lenses. They may, however, give rise to major fitting problems, for example in the case of irregular astigmatism or keratoconus. If adequate centration and stabilization of the contact lens cannot be achieved, corrective corneal surgery may be required.

Recurrent corneal erosions contraindicate contact lens wear for cosmetic or optical indications, as contact lenses—particularly hard lenses—can repeatedly shear the poorly anchored epithelium from the underlying tissue, causing severe pain. Nonetheless, soft, ultra-thin bandage lenses are an excellent form of treatment for chronic recurrent erosions, as well as for bullous keratopathy, which is often accompanied by endothelial dystrophy. In summary, patients with these conditions should only wear contact lenses for therapeutic indications.

Symptoms: Feeling of dryness and grittiness; eye-rubbing; increased ocular temperature; glare.

Clinical findings: Persistent conjunctival injection; blurred vision; irregular changes of refractive error while lenses are worn.

Fig. 426 Dry eye in a wearer of hard contact lenses, dull lens surface, relative tear deficiency, qualitative deficit, wetting problem.

Fig. 427 Dry eye in a wearer of hard contact lenses, air bubbles in the tear lens, quantitative tear deficit.

Fig. 428 Dry eye in a wearer of hard contact lenses, air bubbles under the contact lens, quantitative tear deficit.

Fig. 429 Dry eye in a wearer of hard contact lenses, bubbles in the tear lens from steep fitting, relative quantitative tear deficit.

Illustration 10 Impairment of corneal metabolism by tear deficiency in the contact lens wearer. Tear deficiency leads to elevation of the temperature of the anterior corneal surface and thus to drying out of the contact lens, which thereby becomes less permeable to oxygen (lower Dk). The cornea is then forced to switch to anaerobic glycolysis, as a result of which lactate and pyruvate build up in the tear fluid. Corneal edema ensues, which further impairs lens motility, blocking exchange of the tear film and completing the vicious circle of corneal metabolic decompensation.

The tear deficiency syndrome often develops gradually over several years and may be misdiagnosed at first, as its symptomatic presentation is more variable than that of many other ophthalmological conditions. At first, patients usually complain only of itching, burning, and the need to rub the eyes. The patient’s report that the lids are stuck together in the morning and difficult to open is often the first indication of a disturbance of tear function. The foreign body sensation becomes progressively intense as contact lenses are worn, and visual problems develop, such as reduced contrast or increased glare. The patient must blink much more frequently. If tear deficiency syndrome in its early stages is not treated, or treated by the patient himself in unsupervised fashion with nonprescription eye drops, chronic conjunctivitis may ensue.

Fig. 430 Dry eye in a wearer of soft contact lenses, wetting problem, mucin deficiency, transient central clouding after each blink.

Fig. 431 Tear deficiency, piggyback system, deficit of aqueous phase, inadequate tear lens under a hard contact lens.

Fig. 432 Dry eye, hard contact lens, air bubble under the lens, deficit of aqueous phase.

Fig. 433 Dry eye, hard contact lens, hydrophobic lens surface, mucin deficiency.

Fig. 434 Tear deficiency, soft contact lens, drying evident after 8 hours of wear, bubbles under the lens.

Fig. 435 Tear deficiency, soft contact lens, bubbles under the lens after 8 hours of wear, surface wetting problem.

Fig. 436 Tear deficiency, soft contact lens, collection of bubbles under the lens, epithelial damage.

Fig. 437 Dried out soft lens, bubble under the lens, poor wetting of the lens surface.

Fig. 438 Tear deficiency. Dried out, deformed soft lens of high water content.

Fig. 439 Tear deficiency. Dried out, deformed soft lens of high water content, bubbles under the lens, epithelial lesion.

Fig. 440 Corneal erosion in a soft lens wearer with tear deficiency, diminished corneal reflex from drying.

Fig. 441 Corneal erosion, incipient bullous separation, tear-deficient soft lens wearer, diminished corneal reflex caused by drying of the corneal surface.

Fig. 442 Corneal edema and epithelial damage due to tear deficiency, hard contact lens, deficit of aqueous phase.

Fig. 443 Epithelial and stromal edema due to tear deficiency, hard contact lens, deficit of the wetting component of tears.

Fig. 444 Decreased slit-lamp reflex from the anterior surface of a soft contact lens, inadequate wetting of the lens material.

Fig. 445 Decreased slit lamp reflex from the anterior surface of a soft contact lens, staining shows stippling of the lens surface, lens desiccated.

Fig. 446 Poor wetting, instability of the tear film on the anterior surface of a hard lens, mucin deficiency.

Fig. 447 Poor wetting, instability of the tear film on the anterior surface of a soft lens.

Fig. 448 Normal BUT: tear film intact at 10 seconds.

Fig. 449 Borderline BUT, break in film at 8 seconds.

Fig. 450 Pathological BUT, break in film at 5 seconds.

Fig. 451 Highly pathological BUT, break in film at 2 seconds.

Fig. 452 Tear deficiency, hard contact lens, rose bengal staining, abrasion below the limbus caused by the lens because of tear deficiency.

Fig. 453 Perilimbal traces of abrasion from wearing hard contact lenses, relative tear deficiency, staining with rose bengal.

Fig. 454 Traces of abrasion from the overlying hard contact lens, tear deficiency, rose bengal staining.

Fig. 455 Hard lens wearer with severe tear deficiency, absolutely unable to wear contact lenses.

Fig. 456 Severe tear deficiency syndrome, absolute contra-indication for contact lenses.

Fig. 457 Tear deficiency, rose bengal test after 8 hours of wearing a RGP lens.

Fig. 458 Tear dysfunction, soft contact lens wearer, traces of conjunctival abrasion, rose bengal staining.

Fig. 459 Tear deficiency, soft lens wearer, traces of abrasion at the limbus, rose bengal staining.

Fig. 460 Tear dysfunction, soft lens wearer, traces of abrasion on the cornea and conjunctiva, rose bengal staining.

Fig. 461 Tear deficiency, soft lens wearer, traces of abrasion in the region covered by the lens haptic, rose bengal staining.

Fig. 462 Corneoscleral lens wearer with dry eye, conjunctival epithelial lesions with marked staining at the limbus, poor fitting, loss of lens.

Fig. 463 Dry eye, aphakia, tear deficiency syndrome. Lens worn without difficulty after insertion of a flow-controller in the lower punctum.

Fig. 464 Blunt trauma from a squash ball in a wearer of soft lenses.

Fig. 465 Perforating wound from a screwdriver; RGP lens wearer.

Fig. 466 Perforating wound from a glass shard; soft contact lens wearer.

The diagnosis of tear deficiency syndrome is established by quantitative and qualitative clinical testing of tear function. Testing is difficult in routine practice, however, because of the small volumes concerned, as compared to other bodily secretions: the average normal daily production of tear fluid is only about 1.0 ml. Thus, tear deficiency syndrome cannot always be reliably diagnosed in its early stage.

This is a simple and easy provocative test for dry eye in the contact lens wearer. A stream of warm air from an electric hair drier is directed at the patient’s open eyes from a distance of 1 m. Patients complaining of an uncomfortable foreign body sensation or dryness within 10 seconds usually suffer from a tear disorder.

Pachymetry

Pachymetry and (better still) micropachymetry are the most accurate diagnostic tests for tear deficiency syndrome in contact lens wearers and enable differentiation of its various stages and clinical types. The central corneal thickness (CCT) is normally 545 ± 20 μm. Values less than 525 μm indicate thinning of the cornea through desiccation, tissue loss, or both; in such cases, the average CCT over the course of the day is below 500 μm. On the other hand, absolute or near-absolute lack of tears can cause marked corneal swelling, to a CCT well over 600 μm. When interpreting CCT values, however, one must remember that the corneal thickness is subject to the influence of various mechanical and metabolic factors when contact lenses are worn. It is therefore advisable to measure the CCT several times over the course of the day. Another, easier way to test for tear deficiency syndrome is to measure the CCT before and after instillation of a drop of artificial tear fluid in the conjunctival sac; if the CCT remains constant over the ensuing 20 minutes, then tear function is adequate.

Thermometry

Measuring the temperature of the anterior segment is a further aid to the diagnosis of tear deficiency syndrome. Infrared thermography of the cornea and conjunctiva provide the clearest documentation of temperature changes, but it requires specialized equipment that is not usually available in routine clinical practice. Instead, the temperature of the anterior segment can be measured with a hand-held thermistor placed on the fold of the closed upper lid. The normal temperature is 35–36°C; elevations are due to relative or absolute tear deficiency. This method can be used to assess the efficacy of treatment for dry eye with eye drops, gels, sprays, or ointments: the longer the decline in temperature persists after one of these products is applied, the more effective the treatment.