Pinkeye (Moraxella bovis)

Pinkeye, medically known as infectious bovine keratoconjunctivitis, is one of the most common and economically significant infectious diseases affecting cattle worldwide. This highly contagious ocular disease is caused primarily by the bacterium Moraxella bovis, though other organisms including Moraxella bovoculi and Mycoplasma species may also contribute to the disease syndrome. The condition is characterized by inflammation of the conjunctiva and cornea, leading to excessive tearing, corneal opacity, ulceration, and in severe cases, permanent blindness. Pinkeye occurs most frequently during summer months when face fly populations peak and environmental conditions favor disease transmission.

While cattle are the primary species affected by classical pinkeye caused by Moraxella bovis, similar conditions occur in sheep and goats caused by related organisms. The disease affects cattle of all ages but is particularly common in young stock, especially calves during their first grazing season when they lack immunity from previous exposure. Geographic distribution is worldwide, with the disease occurring wherever cattle are raised, though prevalence varies considerably based on environmental conditions, management practices, and fly populations. Pasture-based operations typically experience higher disease rates than confinement systems due to increased fly exposure and sunlight intensity.

The economic impact of pinkeye extends well beyond treatment costs, affecting multiple aspects of cattle production and welfare. Affected animals experience significant pain and discomfort, leading to reduced grazing time, decreased weight gain, and poor feed conversion efficiency. Studies have documented weight loss of 15 to 40 pounds in affected calves compared to healthy contemporaries. Additional losses occur through decreased milk production in affected cows, reduced sale prices for calves with visible eye damage, labor costs for treatment, and occasional permanent blindness requiring culling of valuable animals. Annual losses in the United States alone are estimated at 150 million dollars or more.

Pinkeye is treatable when detected early and addressed appropriately, though treatment success depends heavily on the stage of disease at intervention. Early cases involving only mild conjunctivitis or superficial corneal ulceration typically respond well to antimicrobial therapy and supportive care, with most animals recovering completely within two to three weeks. Advanced cases with deep corneal ulceration, corneal perforation, or secondary complications carry more guarded prognosis and may result in permanent corneal scarring or blindness despite aggressive treatment. Prevention through fly control, vaccination, and environmental management represents the most effective approach to reducing pinkeye impact in cattle operations.

The primary causative agent of pinkeye in cattle is Moraxella bovis, a gram-negative bacterium that colonizes the conjunctival mucosa and corneal surface. This organism produces several virulence factors essential for disease development, including pili that enable attachment to corneal epithelial cells, cytotoxins that damage tissue, and enzymes that break down corneal collagen and facilitate ulcer progression. More recently, Moraxella bovoculi has been recognized as an additional causative agent, either alone or in combination with Moraxella bovis, and may contribute to cases that fail to respond to traditional treatments. Mycoplasma species, particularly Mycoplasma bovoculi, can cause conjunctivitis and may predispose the eye to secondary Moraxella infection.

Genetic factors influence pinkeye susceptibility primarily through eye pigmentation characteristics rather than direct immune response differences. Cattle with non-pigmented eyelids and faces, particularly those lacking dark skin around the eyes, face substantially higher pinkeye risk compared to animals with pigmented eye areas. This relationship exists because unpigmented tissue provides less protection against ultraviolet radiation, which damages the corneal surface and increases susceptibility to bacterial colonization. Hereford cattle, with their characteristic white faces, traditionally suffer high pinkeye rates, while breeds with pigmented eye areas such as Angus experience lower disease incidence under similar conditions.

Environmental factors play crucial roles in pinkeye transmission and disease severity. Face flies serve as mechanical vectors, transmitting Moraxella organisms between animals as they feed on ocular secretions. High fly populations during summer months directly correlate with pinkeye outbreak severity. Ultraviolet radiation from intense sunlight damages the corneal epithelium, creating entry points for bacterial colonization. Tall grass and weeds cause physical eye irritation during grazing, further compromising corneal integrity. Dust, wind, and plant awns or seeds cause additional mechanical trauma. Hot, dry conditions concentrate cattle around limited water sources, facilitating direct transmission between animals.

Several risk factors beyond genetics and environment influence individual animal susceptibility to pinkeye. Age affects disease patterns, with young animals lacking previous exposure and immunity facing higher risk during their first grazing season. Concurrent diseases that suppress immune function may increase susceptibility. Nutritional deficiencies, particularly of vitamin A, compromise corneal health and immune function. Stress from any source including transportation, weaning, or social disruption may predispose animals to infection. Previous eye injury or scarring provides sites for bacterial attachment and disease establishment.

The pathophysiology of pinkeye begins with bacterial attachment to the corneal surface, facilitated by prior damage from ultraviolet light, mechanical trauma, or other factors. Once attached, Moraxella organisms multiply and produce cytotoxins that kill epithelial cells, creating the characteristic corneal ulcer. The immune response brings inflammatory cells and blood vessels into the normally avascular cornea, causing the visible opacity and vascularization. Neutrophils release enzymes that may worsen tissue damage even as they attempt to eliminate the infection. In severe cases, ulceration can extend through the full thickness of the cornea, resulting in perforation and potential loss of the eye.

Early warning signs of pinkeye are subtle and require careful observation to detect before the disease progresses to more obvious stages. The first indicators typically include increased tearing and blinking of the affected eye, with animals showing sensitivity to bright light by keeping the eye partially closed or seeking shade more frequently than normal. A small grayish spot may appear in the center of the cornea, representing the initial site of bacterial invasion and tissue damage. Affected animals may shake their heads or rub the affected eye against objects or other animals due to irritation. During this early stage, cattle may still graze and behave relatively normally, making detection challenging in large pasture groups.

Clinical symptoms become progressively more apparent as the disease advances through recognized stages. Stage one involves excessive tearing, light sensitivity, and a small central corneal ulcer typically one to two millimeters in diameter. Stage two shows enlargement of the ulcer to three to six millimeters with visible corneal edema causing a blue-white haziness around the lesion. Stage three involves further ulcer enlargement covering much of the cornea, intense opacity, and blood vessels growing inward from the limbus. Stage four represents severe disease with deep ulceration, possible corneal perforation, and dense scarring. The progression through these stages typically occurs over seven to ten days without treatment, though some cases progress more rapidly.

Behavioral changes accompany the physical symptoms and often provide the first indication of disease to observant caretakers. Affected cattle frequently position themselves in shade or with the affected side away from bright sunlight. Grazing behavior decreases as animals spend more time with eyes closed or head lowered to avoid light exposure. Social behavior may change, with affected animals separating from the group or showing reduced activity levels. Cattle with bilateral pinkeye may be reluctant to move and may bump into objects due to impaired vision. Some animals become more difficult to handle due to the combined effects of reduced vision and discomfort.

Physical signs visible on examination include characteristic ocular changes that progress in severity. Excessive lacrimation produces tear tracks down the face, sometimes with secondary hair loss or skin irritation from chronic moisture. The conjunctiva appears reddened and swollen, with the third eyelid potentially becoming more visible. The cornea shows opacity ranging from subtle haziness in early cases to dense white or yellow discoloration in advanced disease. Central corneal ulcers appear as depressed areas that may stain positive with fluorescein dye. Blood vessels extending from the edge of the cornea toward the ulcer create a characteristic pink appearance that gives the disease its common name. In severe cases, purulent discharge may be present.

Symptom progression without treatment follows a predictable pattern over approximately two to three weeks. Initial tearing and mild opacity advance to obvious ulceration within the first few days. The ulcer enlarges and deepens during the first week, with vascularization becoming prominent during the second week as the eye attempts to heal. Most untreated cases begin to show improvement by three weeks as immune response and corneal healing mechanisms gain control. However, the cornea rarely returns to complete clarity, with permanent scarring remaining in most cases. The severity of final scarring directly relates to the maximum extent of ulceration achieved before healing begins.

Emergency symptoms requiring immediate veterinary intervention include signs of corneal perforation such as sudden change in eye shape, visible iris prolapse through the corneal defect, or dramatic decrease in apparent eye size due to aqueous humor loss. Severe swelling of the eye or eyelids beyond typical disease presentation may indicate secondary infection or abscess formation. Complete lack of vision in both eyes creates a welfare emergency requiring immediate attention. Any animal with pinkeye that develops signs of systemic illness such as fever, depression, or loss of appetite may have secondary complications requiring aggressive intervention.

Clinical examination provides the primary basis for pinkeye diagnosis in cattle, with the characteristic appearance of corneal ulceration in appropriate environmental and seasonal context being highly suggestive of the condition. Examination begins with observation of the animal from a distance to assess symmetry, discharge, and obvious lesions. Closer examination in a restrained animal allows assessment of the cornea, conjunctiva, and anterior chamber. Fluorescein staining, in which a yellow-green dye is applied to the corneal surface, highlights ulcerated areas that lack the protective epithelium and take up the stain. This test helps differentiate active ulcers from healed scars and defines ulcer extent. The examiner evaluates ulcer depth, position, and characteristics to determine disease stage and guide treatment decisions.

Diagnostic testing beyond clinical examination may be pursued in some situations, particularly for research purposes, vaccine development, or investigation of unusual outbreaks. Bacterial culture from conjunctival swabs can identify Moraxella bovis or bovoculi and provide isolates for antimicrobial sensitivity testing, though empirical treatment typically begins before culture results are available. Polymerase chain reaction testing offers more rapid and sensitive pathogen detection. Cytology from corneal scrapings reveals inflammatory cells and may show bacterial organisms. In valuable animals with severe or atypical disease, more advanced diagnostics including tonometry to measure intraocular pressure or ultrasonography to evaluate internal ocular structures may be warranted.

Differential diagnosis for bovine pinkeye includes other causes of ocular disease that may present with similar signs. Infectious bovine rhinotracheitis virus can cause conjunctivitis and keratitis, though typically with more systemic illness and involvement of the upper respiratory tract. Foreign bodies lodged under the eyelids or on the corneal surface cause localized inflammation and ulceration. Neoplasia, particularly squamous cell carcinoma common in cattle with non-pigmented eyes, may present with chronic eye lesions. Parasitic infections including Thelazia eyeworms cause conjunctivitis with visible parasites on careful examination. Trauma from fighting, handling, or environmental hazards produces corneal damage that may become secondarily infected. Congenital eye abnormalities occasionally mimic acquired disease.

Herd-level diagnostic considerations become important when pinkeye affects multiple animals or when evaluating prevention program effectiveness. Attack rates within groups help assess outbreak severity and identify potential risk factors. Comparison between groups with different management, breed composition, or environmental exposure provides insights into contributing factors. Collection of isolates for strain typing may reveal whether a single outbreak strain is responsible or multiple introductions have occurred. Evaluation of fly populations and species provides context for vector control recommendations. Assessment of pasture conditions, water access, and shade availability identifies environmental factors requiring modification.

Emergency treatment of severe pinkeye cases focuses on preventing corneal perforation and preserving vision through aggressive antimicrobial and supportive therapy. Animals with deep ulcers at risk of perforation may benefit from temporary tarsorrhaphy, a procedure in which the eyelids are partially sutured closed to protect the corneal surface during healing. Third eyelid flaps, in which the third eyelid is sutured over the cornea, provide similar protection while maintaining some vision. Atropine drops dilate the pupil and reduce painful ciliary spasm in eyes with significant inflammation. Severe cases warrant systemic anti-inflammatory therapy in addition to local treatment. Animals with suspected or confirmed perforation require immediate veterinary evaluation to determine whether the eye can be salvaged.

Medical management with antimicrobials forms the mainstay of pinkeye treatment, with multiple administration routes and products available. Subconjunctival injection of long-acting antibiotics, typically penicillin or oxytetracycline, provides high local drug concentrations directly at the site of infection. This approach is highly effective when properly performed but requires proper restraint and technique. Topical ophthalmic preparations allow direct application but require frequent repeated treatments for adequate effect. Systemic antibiotics including long-acting oxytetracycline or tulathromycin achieve therapeutic levels in ocular tissues and may be preferred for treating multiple animals. Withdrawal times must be observed for all antimicrobials, with accurate records maintained documenting treatment details.

Surgical options for pinkeye are limited but may be appropriate in specific circumstances. Third eyelid flaps and temporary tarsorrhaphy as described above represent the most common surgical interventions, providing physical protection rather than addressing the infection directly. In cases of corneal perforation with iris prolapse, surgical repair may be attempted in valuable animals, though success rates are variable. Enucleation, or surgical removal of the eye, becomes necessary in cases of severe damage where the eye cannot be salvaged and ongoing pain or risk of infection from a blind, damaged eye makes removal the most humane option. These procedures require appropriate anesthesia and surgical facilities.

Supportive care measures enhance treatment success and promote faster healing. Moving affected animals to shaded areas reduces ultraviolet exposure that continues to damage the compromised cornea. Fly control on affected animals through individual treatment with insecticides or use of fly masks reduces both irritation and ongoing bacterial transmission. Providing easy access to feed and water ensures adequate nutrition during recovery, which supports immune function and tissue healing. Separation of affected animals from healthy herdmates reduces transmission risk, though this must be balanced against the stress of social isolation. Monitoring for treatment response guides decisions about continuation or modification of therapy.

Herd treatment strategies become necessary during outbreaks affecting multiple animals. Mass treatment approaches including use of oxytetracycline in mineral mixes, water treatments, or long-acting injectable products administered to all animals may help control rapidly spreading outbreaks. However, individual treatment of affected animals typically produces better outcomes than mass medication approaches. Aggressive fly control during outbreaks helps interrupt transmission and reduce new case development. Temporary housing of cattle in shaded facilities may be beneficial where available. Examination and treatment prioritization ensures the most severely affected animals receive prompt attention.

Treatment decisions balance welfare concerns, economic factors, and practical considerations. Early treatment when ulcers are small produces the best outcomes with shortest treatment duration and least scarring. The value of the individual animal influences how aggressively treatment is pursued, with intensive care protocols appropriate for valuable breeding stock that would not be economically justified for commercial animals. In severe outbreaks, triage approaches prioritize treatment of early-stage cases most likely to respond well while providing palliative care to advanced cases. Consultation with a veterinarian helps develop appropriate treatment protocols for the specific operation and outbreak circumstances.

Recovery timeline for pinkeye varies considerably based on disease severity at treatment initiation, treatment protocol employed, and individual animal factors. Mild cases treated early typically show improvement within two to three days, with complete resolution of clinical signs within seven to ten days. Moderate cases with established corneal ulcers require two to four weeks for clinical healing, though some corneal opacity may persist longer or permanently. Severe cases with deep ulceration or complications may take four to six weeks or longer to stabilize, often with significant permanent scarring. The vascularization that develops during healing gradually regresses over several months, and final corneal appearance may not be evident for three to six months after disease resolution.

Post-treatment monitoring ensures adequate response and allows early intervention if complications develop. Animals should be re-examined within 24 to 48 hours of initial treatment to assess response, with improvement in comfort level and stabilization or reduction of ulcer size expected. Daily observation continues until obvious improvement is evident. Fluorescein staining at follow-up examinations confirms ulcer healing progression. Animals failing to improve within expected timeframes may require treatment modification, additional diagnostics, or consideration of alternative diagnoses. Recording treatment outcomes for individual animals creates a database useful for protocol evaluation and refinement.

Prognosis depends primarily on the extent of corneal damage at treatment initiation and complications encountered during healing. Animals treated during stage one or early stage two disease have excellent prognosis for complete or near-complete recovery with minimal permanent scarring. Stage three cases typically recover with variable amounts of corneal scarring that may affect vision but usually allows functional sight. Advanced stage four cases with corneal perforation carry guarded prognosis for vision preservation, though eyes may sometimes be saved with aggressive treatment. Bilateral disease carries worse prognosis due to cumulative effect on vision and greater impact on animal welfare and productivity.

Return to production considerations include both timing and potential lasting effects of the disease episode. Weight gain typically normalizes once animals recover and resume normal grazing behavior, though some deficit compared to unaffected animals may persist. Permanent corneal scarring does not necessarily preclude productive lives, as cattle adapt well to partial visual impairment. However, animals with significant vision loss may face challenges in extensive grazing environments and may be better suited to more confined production systems. Breeding soundness is not typically affected by pinkeye, though valuable animals with severe scarring may face reduced sale values due to cosmetic appearance.

Vaccination against pinkeye represents a cornerstone of prevention programs, though vaccine efficacy has historically been variable due to the antigenic diversity of Moraxella organisms. Traditional bacterin vaccines containing Moraxella bovis provide some protection but may not cover all strains present in a given environment. Autogenous vaccines prepared from isolates collected from affected animals in a specific herd may provide better protection against the particular strains causing problems in that population. Vaccination should be administered two to four weeks before anticipated peak risk periods, typically late spring to early summer in most regions. Booster doses may be indicated mid-season during extended risk periods or in naive populations.

Fly control measures target the primary vector responsible for pinkeye transmission and significantly reduce disease incidence when effectively implemented. Face flies are the most important vector and should be the primary target of control efforts. Pour-on and spray insecticides applied directly to cattle provide temporary relief but require frequent reapplication. Insecticide-impregnated ear tags, while convenient, may lose effectiveness as resistance develops in fly populations. Dust bags and oilers positioned where cattle must pass daily provide ongoing passive treatment. Feed-through insecticides that kill fly larvae developing in manure reduce overall populations. Biological control using parasitic wasps that attack fly pupae can supplement chemical approaches.

Environmental modification reduces pinkeye risk factors and transmission opportunities. Providing adequate shade structures allows cattle to avoid peak ultraviolet exposure during midday hours, reducing corneal damage that predisposes to infection. Clipping or managing tall vegetation in pastures prevents seed heads and rough plant material from causing mechanical eye irritation. Ensuring adequate water sources prevents congregation that facilitates direct transmission. Strategic pasture rotation moves cattle away from areas with high fly pressure. Maintaining clean, dry bedding in confined areas reduces fly breeding habitat.

Management practices beyond environmental modification further reduce pinkeye incidence. Examining new arrivals for eye disease and isolating affected animals prevents introduction of infection to susceptible populations. Early identification and treatment of affected individuals reduces the reservoir of infection and ongoing transmission. Removing or isolating carrier animals that experience repeated infections may reduce overall herd disease pressure. Maintaining good nutritional status, particularly adequate vitamin A levels, supports eye health and immune function. Reducing stress through gentle handling and avoiding unnecessary procedures during peak risk periods may reduce susceptibility.

Quarantine and monitoring protocols protect herds from pinkeye introduction and enable rapid response when cases occur. New cattle should be examined upon arrival and monitored closely for two to three weeks before introduction to main herds. Purchased animals from sales or multiple sources pose highest risk for introducing new pathogen strains. During outbreaks, affected animals should be separated from healthy cattle when practical to reduce transmission. Increased monitoring frequency during high-risk seasons enables early case detection and treatment. Maintaining records of cases by location, animal source, and timing helps identify patterns and refine prevention strategies.

Daily management practices for pinkeye control integrate disease monitoring with routine cattle handling activities. Observation of cattle during daily checks or feeding provides opportunities to identify early cases. Personnel should be trained to recognize subtle signs including increased tearing, light sensitivity, and behavioral changes suggesting ocular discomfort. Animals identified as potentially affected should be gathered and examined more closely at the next available opportunity. During high-risk seasons, more frequent monitoring may be warranted, particularly for high-value animals or groups with active cases. Consistent observation by familiar personnel improves detection rates as changes from normal behavior are more readily noticed.

Facility design and management influence pinkeye incidence and should be optimized where possible. Handling facilities that allow safe restraint and examination of individual animals enable prompt diagnosis and treatment. Adequate shade structures positioned throughout pastures provide ultraviolet protection and reduce environmental risk factors. Water source distribution prevents congregation that facilitates transmission. Dust control in working areas and around feeding sites reduces mechanical eye irritation. Designing facilities to minimize handling stress supports overall animal health and may reduce disease susceptibility. For operations with chronic pinkeye problems, investment in facility improvements may provide long-term economic returns through reduced disease losses.

Herd health programs should include pinkeye as a component of comprehensive cattle health management. Veterinary consultation helps develop prevention and treatment protocols appropriate for the specific operation, local pathogen strains, and environmental conditions. Vaccination program timing and product selection should be evaluated annually based on previous season performance. Fly control strategies require regular assessment and adjustment as resistance patterns change and new products become available. Integration of pinkeye prevention with other herd health activities improves efficiency and reduces cattle stress from handling.

Record keeping enables evaluation of pinkeye prevention and treatment programs over time. Individual animal records should document disease occurrence, treatments administered, and outcomes observed. Herd-level records track incidence rates, timing of outbreaks, and identification of high-risk groups or locations. Economic records capture treatment costs, labor inputs, and production impacts for cost-benefit analysis. Comparing disease incidence before and after implementation of control measures demonstrates program effectiveness. Records of vaccine products and fly control methods facilitate troubleshooting when programs appear to fail.

Economic analysis guides resource allocation for pinkeye control and helps justify prevention investments. Treatment costs include medications, veterinary services, labor, and facilities used. Production losses from reduced weight gain, decreased milk production, and impaired breeding performance often exceed direct treatment costs. Marketing penalties for calves with visible eye defects reduce sale revenues. Labor costs for increased monitoring and treatment during outbreaks can be substantial. Prevention program costs including vaccines, fly control products, and facility improvements should be weighed against anticipated reductions in disease losses. Most economic analyses support investment in prevention programs for operations experiencing significant pinkeye incidence.

Eye pigmentation represents the primary breed-associated risk factor for pinkeye in cattle, with non-pigmented periocular skin providing less protection against ultraviolet radiation damage. Hereford cattle, with their characteristic white faces and often non-pigmented eyelids, traditionally experience the highest pinkeye rates among beef breeds. Other white-faced breeds and breed crosses including Hereford-influenced animals face similar increased risk. Simmental cattle often have non-pigmented eye areas and show elevated susceptibility. Charolais cattle, while light colored, may have better pigmentation around the eyes than Herefords in some populations. Among dairy breeds, Holsteins with white facial markings that extend around the eyes face higher risk than those with pigmented eye areas.

Breed comparisons extend beyond pigmentation to include other potential factors affecting disease susceptibility. Angus and other black-hided breeds with fully pigmented faces and eyelids consistently show lower pinkeye rates under similar management conditions. Red Angus cattle also benefit from pigmented eye areas. Brahman and Brahman-influenced cattle demonstrate reduced pinkeye susceptibility, attributed both to eye pigmentation and potentially to other genetic differences in immune response or tear composition. Some research suggests differences in tear film properties or eyelid conformation may contribute to breed differences independent of pigmentation.

Genetic selection offers opportunities to reduce pinkeye susceptibility within herds over time. Selecting bulls with well-pigmented eye areas improves offspring pigmentation and reduces pinkeye risk. Expected progeny differences for eye pigmentation are available for some breeds and can guide sire selection decisions. Within Hereford populations, selection for pigmented eyes has been ongoing for decades, with many contemporary Herefords showing much better eye pigmentation than historical populations. Culling animals that experience severe or repeated pinkeye episodes removes potentially susceptible genetics from the breeding population. Crossbreeding programs incorporating breeds with pigmented eyes can quickly improve offspring resistance. Research continues to identify additional genetic factors beyond pigmentation that influence pinkeye susceptibility.

Pinkeye frequently occurs alongside other conditions that may complicate diagnosis, treatment, or recovery. Infectious bovine rhinotracheitis virus causes respiratory disease but can also produce ocular signs including conjunctivitis and corneal opacity that may be confused with or occur concurrently with bacterial pinkeye. Concurrent IBR infection may predispose to Moraxella colonization or worsen the severity of pinkeye lesions. Other respiratory pathogens that cause ocular signs as part of systemic illness include bovine viral diarrhea virus and Mycoplasma species. Nutritional deficiencies, particularly vitamin A deficiency, compromise corneal health and may increase pinkeye susceptibility while also causing other ocular abnormalities.

Several conditions share clinical features with pinkeye and must be considered in differential diagnosis. Squamous cell carcinoma, or cancer eye, is common in cattle with non-pigmented periocular skin and may initially resemble chronic pinkeye lesions before progressing to obvious tumor formation. Foreign bodies lodged under the eyelids or on the corneal surface cause localized inflammation and ulceration that may appear similar to infectious pinkeye. Thelazia eyeworms cause conjunctivitis with visible nematodes on close examination. Trauma from various sources produces corneal damage that may become secondarily infected with Moraxella or other bacteria. Chemical irritation from fly sprays or environmental agents can cause ocular inflammation.

Complications of pinkeye extend beyond the primary corneal ulceration and may cause additional clinical problems. Corneal perforation with iris prolapse represents the most severe complication, requiring emergency intervention to preserve the eye. Secondary bacterial infection of damaged tissue may cause orbital cellulitis or abscess formation. Chronic corneal scarring following healed ulcers may predispose to recurrent problems or contribute to squamous cell carcinoma development. Synechiae, or adhesions between iris and lens or cornea, may develop in eyes with severe inflammation and affect long-term function. Phthisis bulbi, or shrinkage of the entire globe following severe damage, may occur in eyes that survive initial injury but suffer irreparable damage.