Abstract
Objectives
The aim of the present study was to evaluate outcomes in cats with lens luxation treated with intracapsular lens extraction (ICLE), medical management or transcorneal lens reduction (TCLR), and to investigate the reasoning behind treatment recommendations.
Methods
Medical records were retrospectively reviewed to identify cats with lens luxation. Data collected included signalment, examination findings, treatment decision and rationale for treatment, and outcome.
Results
Records were reviewed for 136 eyes from 115 cats. Male cats (77%) were overrepresented. Of the eyes, 83/136 (61%) were non-visual on presentation. Medical management was initially elected for 79/136 (58%) eyes, enucleation for 32/136 (24%), ICLE for 12/136 (9%) and TCLR for 7/136 (5%), while no treatment was elected for 3/136 (2%) eyes. Two cats were euthanized (2/136 eyes, 1%) and one eye underwent diode laser cyst ablation. TCLR was not successful in any eyes. Of eyes with follow-up, 12/13 (92%) eyes that underwent ICLE as primary or secondary management were visual and normotensive (intraocular pressure [IOP] <25 mmHg), while 19/50 (38%) medically managed eyes were visual and normotensive. However, 33/50 (66%) medically managed eyes were normotensive at last recheck and 17/23 (74%) medically managed eyes that were visual on presentation remained visual at last recheck. Treatment rationale was noted for 94 eyes. Factors cited included visual status (40%), perceived comfort (36%), age or medical history (29%), financial limitations (12%), inability to medicate (10%), other ocular examination findings (9%) and potential risk of feline post-traumatic ocular sarcoma after ICLE (7%).
Conclusions and relevance
TCLR does not appear to be a viable treatment modality in cats. Medical management of lens luxation may produce acceptable results for IOP control and retention of vision when ICLE is not possible. Providing cat owners with accurate information about outcomes and financial implications of treatment options for lens luxation is critical.
Plain language summary
This study looked at treatments for cats with lens luxation. Lens luxation most commonly occurs secondarily to chronic uveitis and can lead to glaucoma and vision loss. The ideal treatment for lens luxation is a surgical procedure to remove the lens (intracapsular lens extraction, or ICLE). Some cats are not good candidates for surgery and some owners cannot afford surgery. In addition, medical decision-making for cats may involve different factors than for dogs. In this study, 58% of cats were treated with eye medications instead of undergoing ICLE. Of those cats, 66% maintained normal intraocular pressure, and 74% of the cats that were visual at time of diagnosis maintained vision with medical treatment instead of ICLE. Cats treated with ICLE also did well, with 92% maintaining vision and normal pressure. Attempted non-surgical repositioning of the lens (transcorneal lens reduction), which may be beneficial in dogs, was not successful in any cats. Reasons given to support treatment decisions involved cats’ overall health, other ocular examination findings and doctors’ beliefs about treatment outcomes in cats, some of which may not be supported by evidence. Medical management may be an acceptable alternative to ICLE in cats with lens luxation, but cat owners should be provided with accurate information about prognosis and future course of treatment. More work is needed to determine which eye medications are most beneficial in treating cats with lens luxation.
Introduction
Lens luxation in domestic cats is thought to occur most commonly secondarily to zonular fiber damage from chronic uveitis. 1 Genetic factors, age-related zonular degeneration or the presence of other ocular conditions, such as cataracts or chronic glaucoma, may also contribute to lens luxation.2 –6 Sequelae to lens luxation can include glaucoma, retinal detachment or corneal endothelial damage, any one of which can cause vision loss and/or discomfort.1,7 Intracapsular lens extraction (ICLE) is considered the optimal treatment for anterior lens luxation in cats, but other potential treatment options may include medical management, transcorneal lens reduction (TCLR) or enucleation. Optimal treatment for subluxation or posterior luxation is less clear.
The largest study to date evaluating feline lens luxation was published over 30 years ago. In that study, which evaluated 345 cats, males and Siamese cats were overrepresented, with the most common age at presentation being 7–9 years. 7 Information on outcomes for the cats in that study was limited. Since then, minimal information on feline lens luxation has been added to the literature aside from a handful of abstracts and small case series. Reported success rates for vision preservation and intraocular pressure (IOP) control after ICLE in cats are in the range of 82–100%.6,8,9 Information regarding success rates for TCLR and medical management is scant. 9
The goal of the present study was to provide an updated overview of the clinical features of feline lens luxation and to report on outcomes for medical management, TCLR and ICLE in a larger population of contemporary cats. In addition, although veterinary ophthalmologists may perceive that outcomes are better for ICLE in cats compared with dogs,1,10 recent work also suggests that owners of cats may approach decisions regarding veterinary care differently from owners of dogs.11 –14 Therefore, another goal of this study was to investigate rationales for treatment choices in cats with lens luxation. Understanding clinician and owner perceptions regarding treatment options may improve decision-making for cats with lens luxation.
Materials and methods
The medical records of the Foster Hospital for Small Animals at the Cummings School of Veterinary Medicine at Tufts University and Tufts Veterinary Emergency Treatment and Specialties were searched in March 2023 to identify records of cats with lens luxation seen by the ophthalmology services between 2007 and 2023. Permission for retrospective use of information contained in medical records for research purposes is considered to be included in the general hospital consent for treatment, and additional ethical approval is not required at our institution for deidentified retrospective studies. Client consent was obtained for all treatment performed.
Cats were selected for inclusion if they were examined by a board-certified veterinary ophthalmologist or ophthalmology resident/specialty intern working under the supervision of a board-certified ophthalmologist and were diagnosed with lens luxation. Cats were excluded if ocular examination findings were not documented in the medical record. Ocular examination consisted of neuro-ophthalmic evaluation, slit lamp biomicroscopy (SL-17; Kowa), binocular indirect ophthalmoscopy (All-Pupil binocular indirect headset; Keeler, 20D or 28D indirect lens; Volk Optical), applanation or rebound tonometry (TonoPen; Reichert Technologies, TonoVet; iCare) and fluorescein staining (I-Glo; JorVet). Data collected from cats meeting the inclusion criteria included signalment, affected eye, IOP at presentation, other ocular findings and previous diagnoses, visual status, initial and secondary management, rationale for management choice, time to last follow-up and final status of the eye. Eyes were considered visual if a menace response was present. Duration of signs before presentation was inconsistently recorded and tended to involve vague descriptions; therefore, this data point was not collected.
Enucleation was performed under general anesthesia using a routine transconjunctival approach. ICLE was performed as previously described, 15 with some variation in clinician preference regarding technique for lens delivery (ie, use of cryoprobe vs manual delivery with viscoelastic and lens loop). TCLR was attempted under sedation using a previously published technique. 16 Descriptive statistics were generated.
Results
The initial medical records search identified 175 cases for review. A total of 136 eyes from 115 cats met the inclusion criteria. Patient characteristics and examination findings at presentation are summarized in Table 1. The most common concurrent examination finding was uveitis in 105 (77%) eyes. Ocular trauma immediately preceding lens luxation was believed to be a factor for three eyes, while four eyes had a reported history of trauma 1 month or more before lens luxation. One cat had recently undergone radiation therapy for a nasal tumor. Most cats (16/21, 76%) with bilateral lens luxation had bilateral involvement at initial presentation; of those that did not, median time to onset in the contralateral eye was 8 months (range 1.5–31).
Characteristics of cats with lens luxation and ocular findings at presentation
Data are n or median (range)
IOP = intraocular pressure
Initial treatment consisted of medical management for 79 (58%) eyes, surgical management for 45 (33%) eyes, TCLR for seven (5%) eyes and euthanasia for two eyes (in two cats; one because of concurrent medical conditions, the other because of vision loss). Treatment was declined altogether for three eyes. Of eyes undergoing immediate surgical intervention, 32 were enucleated, 12 underwent ICLE, and transcorneal diode laser ablation of uveal cysts posterior to the iris was performed as primary management in one eye with a subluxated lens (this cat presented with an anterior lens luxation in one eye, with no cysts noted in that eye; laser cyst ablation was elected in the other eye to decrease stress on the zonular fibers in the eye with the subluxation). Owners declined initial treatment recommendations for 25 (18%) eyes. For 21 eyes, enucleation was recommended, but either medical management (18 eyes) or no treatment (three eyes) was elected by the owner. For four eyes, ICLE was recommended, but medical management (three eyes) or enucleation (one eye) was elected.
Secondary management was implemented for 19 (14%) eyes. In total, 11 medically managed eyes were eventually enucleated (seven because of increased IOP and perceived discomfort, three owing to difficulties in administering topical medications and one because of development of a descemetocoele) and one medically managed eye underwent ICLE to address persistent discomfort despite normal IOP. TCLR attempted as initial management in six eyes was unsuccessful because of failure of the lens to move posterior to the iris (TCLR inadvertently occurred in one eye during preparation for ICLE; recurrent luxation was documented in that eye within 1 week). Three of the eyes in the TCLR group were subsequently treated with ICLE, while two eyes were managed medically and two eyes were enucleated.
A total of 21 different treatment regimens utilizing 11 different topical medications were elected for medically managed eyes. In total, 41 eyes were treated with dorzolamide, 36 eyes with a topical non-steroidal anti-inflammatory drug (NSAID) and 31 eyes with a topical steroid. The most common regimens were combination therapy with dorzolamide and a topical NSAID (18 eyes), followed by steroid monotherapy (11 eyes) and dorzolamide monotherapy (eight eyes). Because of the variety of treatment regimens and relatively small number of eyes per treatment regimen with follow-up, no attempt was made to compare the efficacy of different treatment regimens in maintaining vision or controlling IOP.
Follow-up information was available for 63 eyes from 53 cats (62% of the 102 eyes that were not initially managed with enucleation or euthanasia). Median time to last follow-up overall was 8 months (range 0.25–100), median time to last follow-up for eyes that had undergone ICLE was 13 months (range 0.75–48) and median time to last follow-up for eyes managed medically was 6 months (range 0.25–100). A visual, normotensive eye was maintained in 12/13 (92%) eyes that had undergone ICLE and were presented for follow-up, and 19/50 (38%) eyes that were managed medically and were presented for follow-up. All (13/13) eyes treated with ICLE had an IOP below 25 mmHg at the time of the last follow-up; 33/50 (66%) medically managed eyes had an IOP below 25 mmHg. Of the medically managed eyes that were visual at time of diagnosis, 17/23 (74%) were visual at the time of the last follow-up. Of the medically managed eyes that were not visual at the time of diagnosis, 3/27 (11%) were visual at the last follow-up. As a result of the small number of eyes with posterior luxations or subluxations, outcomes were not compared based on lens location at presentation.
Histopathologic evaluation was performed on 29 enucleated eyes from 28 cats. Lymphoplasmacytic uveitis was documented in 22 eyes. Infectious organisms were not found in any eyes. A diagnosis of lymphoma was made in two eyes. Four eyes had evidence of lens capsule rupture, and free lens material was noted in two additional eyes; none of the six eyes with lens disruption had a reported history of intraocular surgery or penetrating trauma. Changes similar to those seen in dogs with primary lens luxation (ie, eosinophilic zonular material adherent to the ciliary epithelium) were not reported in any eyes.
Treatment rationale was documented in the record for 94/136 (69%) eyes. Because of the retrospective nature of this study, it was often unclear whether treatment rationales were primarily generated by clinicians or by cat owners. Multiple factors were cited for some cats. Stated reasons for treatment recommendations or decisions included eye-, cat- and owner-related considerations as well as concerns about future events related to treatment choices. Most common rationales for treatment decisions included visual status (38/94, 40%), perceived comfort level (34/94, 36%), systemic health considerations (27/94, 29%) and financial limitations (11/94, 12%). Of note, perceived risk of post-traumatic sarcoma after ICLE was cited as a rationale for non-ICLE treatment choices in 7/94 (7%) eyes. Treatment rationales are further detailed in Table 2.
Rationales cited in the medical record for initial treatment choices for cats with lens luxation*
Detail regarding reasoning was rarely included, and it was not possible in many cases to determine whether rationales were primarily based on clinician assessment/opinions or owner desires. Perceived ability to tolerate anterior lens luxation was based on described anatomical differences in anterior chamber depth 10
Enuc = enucleation; Euth = euthanasia; ICLE = intracapsular lens extraction; TCLR = transcorneal lens repositioning
Discussion
Cats with lens luxation identified in this study were predominantly male, as in prior studies.7 –9 However, cats in this study were older at the time of initial presentation, with a median age of 12 years compared with 8–10 years in earlier work.7,9 The reason for the difference in age is unclear, but could be related to better overall healthcare for contemporary cats or later exposure to infectious diseases linked to the development of uveitis. Unfortunately, information about cat lifestyle (ie, whether the cat was allowed to roam outdoors) was generally not included in the medical record, and infectious disease testing was not consistently performed.
Uveitis was a common finding in cats in this study, with 77% of eyes receiving a diagnosis of uveitis at the time that lens luxation was identified, compared with 20–68% of eyes in previous studies.7,9 However, cataracts were less frequently noted in feline eyes with lens luxation in this study (38% of eyes) than in previous work (73–80%).7,9 Mean IOP at presentation was also lower in this population of cats (15 mmHg) than in previous studies (18–25 mmHg), and cats were less likely to present with IOP above 25 mmHg (24% as opposed to 35–39%).7 –9 However, the percentage of eyes in the current study lacking a menace response at the time of presentation (61%) is in line with the 56–70% of eyes found to be non-visual at the time of presentation in prior studies (note that the authors of those studies did not specify what parameters they used to assess vision status).7,9
Outcomes for ICLE were similar to those in previous studies and support ICLE as a treatment for feline lens luxation, with 92% of eyes visual and normotensive at last evaluation, compared with 82–100% in earlier studies.7 –9 The current study is the first to report on a large population of cats with lens luxation managed medically and the first to report on feline eyes in which TCLR was attempted. Outcomes in the cats described here confirm the common but previously unevaluated belief that TCLR is not a viable option in cats, as the lens failed to move posterior to the iris in all eyes in which TCLR was attempted. Reported initial success rates for TCLR in dogs are in the range of 73–90%.16 –18 Reasons for the failure of TCLR in cats are not clear, but could be due to species-specific differences in vitreous consistency or lack of age- or disease-related vitreous degeneration in feline eyes. Published information about the feline vitreous is minimal. 1
Medical management produced relatively favorable outcomes for cats in this study, with 66% of eyes with follow-up remaining normotensive (IOP <25 mmHg) and 74% of initially visual eyes maintaining vision at last follow-up. These findings suggest that medical management may be a viable option, particularly in cats for which surgery is not an option because of medical conditions or owner finances. It should be noted, however, that follow-up times were limited in many cats, with a median time to last follow-up of 8 months. More information is needed about longer term outcomes for medical management in cats with lens luxation. More work is also required to determine optimal medical management strategies for cats with lens luxation, as the variability in medication regimens noted in the current study precludes any determination about best practices.
As noted, overall follow-up was poor, with no follow-up available for 38% of the eyes that were not initially treated with enucleation or euthanasia. Follow-up time for the remaining 62% of eyes was short. Moreover, treatment recommendations were declined for 18% of eyes. These findings are in agreement with what is known about differences between cats and dogs regarding veterinary care. Cat owners are less likely to bring their pet to the veterinarian, spend less money on veterinary care and seek lower-cost care more frequently than dog owners.11,13,19 Cats are less likely to be insured, 13 and dogs are twice as likely as cats to receive specialist care. 12 Factors cited to explain these discrepancies include lack of knowledge on the part of owners, difficulty in catching and transporting cats, past stressful experiences at the veterinary hospital, difficulty recognizing signs of pain in cats and lower pet attachment scores.11,13,14,20 Cats are also perceived as more independent and requiring less care, and pet cats are acquired unintentionally more often than pet dogs.11,14 Furthermore, cat owners report more challenges in medicating their pets than dog owners. Over half claim that medicating their cat damaged their bond with their pet, and nearly as many owners report that their cat attempted to bite or scratch them when they tried to administer medication.21,22 Cat owners also state that they are frequently not provided with guidance regarding techniques for medication administration.21,22
Although information regarding treatment decisions in dogs with lens luxation has not been published, the relatively low number of ICLEs performed in the cats identified in this study – despite evidence suggesting that ICLE outcomes are favorable in cats – prompted evaluation of treatment rationales. Medical records often lacked information on the factors involved in decision-making, and the information available was necessarily subjective. A prospective survey of factors guiding treatment decisions would be valuable in this context. Nevertheless, several common themes emerged, which may provide opportunities to improve communication with cat owners and support more fully informed decisions about their pet’s care.
Vision status (as assessed by presence or absence of menace response) and perceived comfort level were the most commonly cited rationales for treatment decisions, followed by systemic health factors that were felt to affect the cat’s ability to tolerate general anesthesia for ICLE or enucleation. Vision status and comfort level were used as justifications for both ICLE and medical management. All eyes undergoing ICLE were visual at presentation, while lack of a menace response was used as justification for medical management or enucleation, with enucleation recommended for eyes that were blind and perceived to be uncomfortable. However, because recognizing signs of discomfort can be challenging in cats, perceived lack of discomfort may not be a justifiable metric to guide treatment decisions in cats with lens instability.20,23 Enucleation was also recommended for eyes with markedly elevated IOP or other pathologies such as retinal detachment or significant corneal ulceration.
Unsurprisingly, treatment choice was also commonly influenced by owners’ financial limitations. In each case in which financial limitations were expressed, medical management was elected. However, it is possible that long-term costs for medical management could exceed those for ICLE, depending on the frequency of rechecks and quantity of medications needed for each approach. In addition, 11/50 (22%) medically managed eyes with follow-up in this study were eventually enucleated, further increasing the cost of care. Providing owners with more accurate information about short- and long-term costs of treatment options, along with expectations regarding outcomes and required rechecks, would permit them to make decisions that best align with their financial means and their goals for their pets.
Perceived or actual inability to administer topical medications also led owners to elect enucleation or no treatment for their cat. Previous work has found that many cat owners report negative past experiences with medication administration or feel that they have received insufficient instruction regarding medication use.21,22 Providing additional education on handling and medicating cats, discussing behavioral management strategies with owners, and making judicious choices regarding number and frequency of medications may all promote selection of globe-sparing treatments in cats with lens luxation.
The beliefs of ophthalmologists and ophthalmology house officers about possible outcomes of therapeutic choices also appeared to contribute to treatment recommendations. This is potentially of concern when these beliefs are not supported by evidence. Medical management was justified in some cats with a statement that anterior lens luxation is better tolerated in cats than in dogs, presumably owing to greater anterior chamber depth in cats. 10 This theory has not been critically evaluated. However, the results of the current study, which suggest that medically managed feline eyes with lens luxation may have acceptable rates of vision preservation and IOP control, potentially support this belief.
Perhaps more detrimentally, theoretical risk of intraocular sarcoma development was cited as a reason not to perform ICLE in seven eyes. Feline ocular post-traumatic sarcoma (FOPTS) is believed to arise from damaged or disrupted lens epithelial cells.24,25 In theory, this type of tumor should not arise in an eye in which ICLE has been performed, since the lens and its capsule are removed without breaching the capsule. A search of the archives of the Comparative Ocular Pathology Laboratory of Wisconsin found only a single case of FOPTS in the 16 feline globes submitted with a prior history of ICLE (M Climans and G Shaw, 2025, personal communication). Findings of lens capsule rupture and/or extracapsular lens material in six of the enucleated eyes in the current study (none of which had a history of intraocular surgery or penetrating trauma) are of uncertain significance in terms of future development of FOPTS in feline eyes with lens luxation. Moreover, chronic uveitis alone is considered a risk factor for the development of other types of post-inflammatory neoplasia. 24 Based on the currently available information, the risk of FOPTS does not seem to be a valid reason for avoiding ICLE in cats.
Conclusions
The results of this study agree with prior work showing that ICLE is an effective treatment for lens luxation in cats. This study also shows, for the first time, that medical management may be a successful strategy for cats with lens luxation who are not able to undergo ICLE because of anesthetic risk or owner financial limitations, and that TCLR is not likely to be successful in cats with anterior lens luxation. Additional work is needed to determine ideal medication regimens (particularly given recent publications highlighting possible systemic effects of topical therapies in cats26 –28) and to assess whether an individual cat’s characteristics may influence success of treatment. Rationales provided to support treatment choices in this study suggest that providing cat owners with more information about treatment costs and likely outcomes and supporting cat owners with training regarding administration of medication may optimize outcomes for cats with lens luxation. Furthermore, ophthalmologists and ophthalmology house officers should seek to provide pet owners with treatment recommendations based on evidence rather than personal belief.
Footnotes
Author note
This paper was presented in part as a poster at the 2023 American College of Veterinary Ophthalmologists meeting.
Conflict of interest
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Ethical approval
The work described in this manuscript involved the use of non-experimental (owned or unowned) animals. Established internationally recognized high standards (‘best practice’) of veterinary clinical care for the individual patient were always followed and/or this work involved the use of cadavers. Ethical approval from a committee was therefore not specifically required for publication in JFMS. Although not required, where ethical approval was still obtained, it is stated in the manuscript.
Informed consent
Informed consent (verbal or written) was obtained from the owner or legal custodian of all animal(s) described in this work (experimental or non-experimental animals, including cadavers, tissues and samples) for all procedure(s) undertaken (prospective or retrospective studies). No animals or people are identifiable within this publication, and therefore additional informed consent for publication was not required.
