Transcorneal aspiration for management of primary iris cysts in the standing horse

BACKGROUND

Equine primary iris cysts are usually incidental findings but, if associated with clinical signs, may require intervention. The use of laser (Nd:Yag or diode) has been reported but requires specialised equipment. Transcorneal aspiration has not been previously evaluated in the standing horse.

OBJECTIVES

To review outcomes of standing transcorneal aspiration of primary iris cysts (STAPIC) in horses.

METHODS

Horses were identified from electronic patient records from 2018 to 2024 across four collaborating centres. Clinical presentation and outcomes were identified and reported using descriptive statistics.

RESULTS

Eighteen horses were identified. Behavioural signs reported included 'spooking' and changes in rideability often associated with jumping. Single large unilateral cysts were present in 11 horses, bilateral cysts in three horses and multiple unilateral cysts in four horses. Following treatment, one horse developed uveitis and fibrin in the anterior chamber associated with needle contact with the iris stroma due to movement, and a second horse developed fibrin within the anterior chamber. Both conditions resolved with anti-inflammatory medication and administration of tissue plasminogen activator. No other adverse effects were reported. Follow-up was available from all horses (median: 6 months, interquartile range [IQR]: 4-11 months) with no recurrence, although one horse developed an iris cyst in the contralateral eye after 3 years. All owners reported improvement in clinical signs, with 61% reporting no further signs.

CONCLUSIONS

STAPIC is an effective and easily accessible alternative for treating iris cysts in horses rarely associated with complications.

Noninvasive diode laser-an effective and safe treatment of iris cysts in 46 eyes of 35 horses

BACKGROUND

Iris cysts in horses are often asymptomatic and noticed incidentally. However, cysts can cause local corneal oedema and erratic behaviour like shying, decreased performance and head-shaking.

OBJECTIVES

To describe the use of diode laser as a noninvasive treatment option for iris cysts in the horse and to document factors influencing its efficacy, associated complications, long-term outcome and rate of recurrence.

STUDY DESIGN

Retrospective case series.

METHODS

Case records of horses treated for iris cysts by diode laser at the Utrecht University Equine Clinic were reviewed between 2008 and 2020. Diagnosis was based on ophthalmic and ultrasonographic evaluation. Long-term follow-up was obtained in two phases, a telephone survey with the owner and a photographic re-evaluation of the treated eyes.

RESULTS

Thirty-five horses were included, with a total of 46 eyes treated. One day after diode laser treatment (short-term), 35/46 treated eyes had a good decrease in cyst size, 7/46 had a moderate effect, 1/46 had a minimal effect, 1/46 had no effect, and in two cases the effect was unspecified. The decrease in size after diode laser treatment in polycystic eyes (odds ratio [OR] 0.381, 95% CI 0.1530-0.724), p = 0.001), thick-walled cysts (OR = 0.139; CI = 0.023-0.726, p = 0.02) and hyperplastic corpora nigra (OR = 0.081; CI = 0.004-0.528, p = 0.03) was significantly less satisfactory, with ORs of 0.381, 0.139 and 0.081, respectively. Minor complications, such as mild reactive uveitis, were reported in 8/46 (17%) eyes. On long-term follow-up (median 19 months; IQR 25.5), clinical signs had diminished or disappeared in most cases (93%) and 83% of the owners would recommend the treatment. Based on long-term photographic re-evaluation (median 32.5 months; IQR 49.75), 2/16 cases of recurrence were seen.

MAIN LIMITATIONS

Retrospective design, follow-up by telephone questionnaire and photographic re-evaluation. Loss to follow-up in the photographic re-evaluation.

CONCLUSIONS

Both short- and long-term results indicate diode laser treatment is a useful and safe option for iris cyst size reduction, with a low risk of recurrence. Presurgical ultrasonography is recommended to assess the feasibility of treatment and to allow for better surgical planning.

Outcomes Following Transcorneal Diode Laser Ablation of Uveal Cysts: 48 Horses (2006-2020)

Uveal cysts can lead to undesirable behaviors and poor performance in horses. Transcorneal laser ablation has been proposed as a safe and effective treatment for uveal cysts suspected of causing behavioral changes but outcomes have been reported in only a small number of horses. In this retrospective study, records were identified for horses who had undergone transcorneal cyst ablation using a diode laser. Information was collected regarding signalment, behavioral or performance issues reported prior to the procedure, and complications. Owners were contacted to provide follow-up information regarding resolution of behavioral issues. Seventy eyes from 48 horses were treated. Undesirable behaviors or performance issues were reported prior to the procedure in 35 horses, and follow-up information was provided for 22 of those horses. Of these 22 horses, 59% of owners reported significant improvements in behavior or performance, 27% reported some improvement, and 14% reported no improvement. No significant complications were reported in association with the procedure. Although follow-up data were available for only a subset of horses, transcorneal diode laser ablation was an effective means of resolving owner-reported behavioral or performance complaints believed to be caused by uveal cysts for many of the horses in this group. Further work is needed to assess effects of uveal cysts on equine behavior and to characterize effects of transcorneal diode laser ablation prospectively.

Idiopathic headshaking: is it still idiopathic?

The clinical syndrome of equine idiopathic headshaking (HSK) was first described in the veterinary literature over 100 years ago, and the disorder continues to be a cause of substantial distress for the horse, frustration for the owner and therapeutic challenge for the veterinarian. This review presents a summary of the current knowledge of clinical signs, signalment, aetiopathogenesis, anatomy, diagnosis and treatment of idiopathic HSK. Recent advances in understanding the pathogenesis of the disease will be discussed with reference to human trigeminal neuralgia, along with the implications this may have for potential therapies.