Congenital Glaucoma in Two Cats and Surgical Repair with Trabeculectomy

Abstract

This current work aims to assess the efficacy and tolerability of trabeculectomy procedure for the management of congenital glaucoma in two cats. Filtration surgery was performed using a limbus-based approach, and flap was raised smoothly to nearly limbus on sclera. Sclera-corneal trabecular block was removed both with surgical knife and microsurgery scissors. Successful result was defined as resolution of leakage with no need for additional surgery, together with maintaining intraocular pressure in the range of 5-21 mmHg with anti-glaucoma medications. In conclusion, trabeculectomy decreased intraocular pressure in cats with congenital glaucoma, there for it may proposed for treatment of related disease.

Full text

İstanbul Üniversitesi
Veteriner Fakültesi Dergisi
Journal of the Faculty of
Veterinary Medicine Istanbul University
İstanbul Üniv. Vet. Fak. Derg. / J. Fac. Vet. Med. Istanbul Univ., 42 (1), 103-105, 2016
doi: 10.16988/iuvfd.2016.32386
Congenital Glaucoma in Two Cats and Surgical Repair with
Trabeculectomy
Murat KİBAR1*, Abdulhekim YARBAG2
1Department of Surgery, Faculty of Veterinary Medicine, Kyrgyz Turkish Manas University, 720044, Bishkek, Kyrgyzstan
2Department of Ophthalmology, Faculty of Medicine, Sakarya University, 54187, Sakarya, Turkey
*Sorumlu Yazar /
Corresponding Author:
Murat KİBAR
e-mail: muratkibartr@yahoo.com
Geliş Tarihi / Received:
27 April 2015
Kabul Tarihi / Accepted:
12 June 2015
Key Words:
Glaucoma, trabeculectomy, cat
Abstract
This current work aims to assess the efficacy and tolerability of trabeculectomy
procedure for the management of congenital glaucoma in two cats. Filtration
surgery was performed using a limbus-based approach, and flap was raised
smoothly to nearly limbus on sclera. Sclera-corneal trabecular block was removed
both with surgical knife and microsurgery scissors. Successful result was defined as
resolution of leakage with no need for additional surgery, together with maintaining
intraocular pressure in the range of 5-21 mmHg with anti-glaucoma medications. In
conclusion, trabeculectomy decreased intraocular pressure in cats with congenital
glaucoma, there for it may proposed for treatment of related disease.
Introduction
Glaucoma is the one of the leading cause of
irreversible visual impairment that affects wide
population of pet animals. In kittens and puppies,
congenital glaucoma is usually secondary to
malformation of the iridocorneal angle and/or
dysgenesis of the structures of the anterior segment
(Amelinckx et al., 2009). The eyes of young animals tend
to enlarge more rapidly and more severely when
glaucoma was present (Amelinckx et al., 2009;
Samuelson and Brooks, 2006). Glaucoma treatments are
directed at reducing intraocular pressure (IOP), either
pharmacologically or surgically. Surgery is performed
when medication and laser treatment failed to control
IOP (Wang et al., 2013).
This current work aims to assess the efficacy and
tolerability of trabeculectomy procedure for the
management of congenital glaucoma in two cats.
Case
Two domestic short hair cats (Felix domesticus), 4
month of age, one is male and other is female, and both
of them weight 1.5 kg were referred to our clinics. They
were siblings. The owner realized that the cats had poor
visual acuity with an opaque stain in their both eyes for
1 month. On ophthalmological examination, the eyes
were seen enlarged and were asymmetrical; the left eye
was larger than the right in case 1 (Figure 1). Right eye
was perforated and occurred iris staphyloma and left
eye was enlarged in case 2 (Figure 2). There were
bilateral conjunctival redness, congestion of the
episcleral vessels and bilateral pupillary dilatation in
both cases. Both the direct and indirect pupillary light
reflexes and the menace response were absent.
Tapetum lucidum was visible by ophthalmoscopy in both
eyes in case 1 and in right eye in case 2. After application
of 0.5% proparacaine hydrocyloride Intraocular
pressures were estimated with a TonoPen (Reichert,
USA), and found ˃40 mmHg (mean IOP: 20.74 mmHg)
preoperatively in right and left eyes in case 1 and in right
eye in case 2.
Trabeculectomy procedure was performed under
general anesthesia with intramuscular injection of
ketamine hydrochloride 20 mg/kg, xylazine 2 mg/kg,
atropin sulfate 0.02 mg/kg, and topical anesthesia was
achieved with proparacaine eye drops. Patients were
intubated endotracheally. Eye was covered up by eye
drape and irrigated by diluted povidone solution. A
partial-thickness 8/0 silk corneal traction suture was
placed at 12 o’clock and the eye pulled down, to gain
exposure to the superior conjunctiva. Upper bulbar
conjunctiva was dissected from limbus and sclera was
Olgu Sunumu Case Report

104 Kibar and Yarbag, J. Fac. Vet. Med. Istanbul Univ., 42 (1), 103-105, 2016
exposed (Figure 3). Mitomisin-C (MMC) was applied 0.2
mg/ml during 1.5 min to sclera and thoroughly irrigated.
Filtration surgery was performed using a limbus-based
approach, and 4×4 mm flap was raised smoothly to
nearly limbus on sclera. Sclero-corneal trabecular block
was removed with surgical knife and microsurgery
scissors (Figure 4). The scleral flap was sutured with
additional interrupted 10/0 nylon suture (Figure 5). The
conjunctival incision was closed with 2 interrupted
sutures and a central mattress-type 8/0 vicryl suture on
a needle to give a water-tight closure. One drop of
dexamethasone 0.5%, combination of travoprost and
timolol, and gentamycine 1% were instilled at the end of
surgery. No other adjunctive treatment was given at the
time of surgery. Additionally, these drops were
administered topically during 5 days.
Figure 1. View of bilateral buphtalmos in case 1. Noted
the enlargement and assymetry in left eye.
Figure 2. View of buphtalmos in right eye and iris
staphylom in left eye in case 2.
Figure 3. View of dissection of bulbar conjunctiva in
case 2.
Figure 4. View of flap raised for sclera and trabeculer
block removed in case 2.
Figure 5. Application of suture to sclera in case 2.

Kibar and Yarbag, J. Fac. Vet. Med. Istanbul Univ., 42 (1), 103-105, 2016 105
IOP measurements were performed before and after
trabeculectomy procedure. After topical instillation of
0.5% proparacaine hydrocyloride eye drops, 1 drop per
eye, with a mean reading of three recordings were
documented per time point. The cats were assessed on
postoperative days 1, 3 and 7. Slightly hyphema was
determined in postoperative period of case 1. The
conjuncttival appearance and the drainage area were
observed. In the treated eyes, a small region of
avascularity which is a transient finding, was noted in the
nasal side of the bleb (<3 mm) within the first 3 days. A
bleb was visible in surgically treated eye throughout the
first 7 days after trabeculectomy. Over the next 7 days the
anterior chamber gradually deepened.
Operation area was associated with elevated,
diffuse, fleshy looking blebs compared with the flat one.
Local reaction was evaluated by the degree of anterior
chamber inflammation and conjunctival vascularity. Bleb
vascularity was assessed as vascular or avascular.
Trabeculectomy procedure was uneventful and
neither discomfort nor inflammation was observed in cats
during the 30 days of postoperative follow-up. Ocular
hypertension was not observed during the same time. The
cornea, iris, lens, vitreous and retina remained normal
and stable. The post-surgery IOP values with a TonoPen
were <30 mmHg. The IOPs at postoperative day 30 were
<20 mmHg. Visual function of both cats was good and no
macroscopic anomaly was determined on eyes.
Discussion
Conservative treatment with medical agents or with
a variety of mechanical methods tried first to cure
congenital glaucoma (Melo et al., 2012; Tomlinson et al.,
1987). However, this technique is still associated with a
significant rate of postoperative complications, including
early hypotony, choroidal detachment, hypotonic
maculopathy, endolphtalmitis, along with others, which
has prompted calls for a better and safer operation
(Samuelson and Brooks, 2006; Wang et al., 2013).
The trabeculectomy requires the creation of an
iridectomy, which is commonly performed, possibly
resulting in greater inflammation and an increased
likelihood of hyphema with latter produce (Wang et al.,
2013). In this case, slightly hyphema was seen in case 1.
IOP values were determined between normal values on
postoperative day 30.
Conjunctival wound healing after glaucoma filtration
surgery is a major determinant of the long term clinical
success of the procedure. Failure of glaucoma filtration
surgery is the most often due to scarring in the
conjunctiva level at the bleb and sclerostomy sites.
Information from previous investigations in animal
models have helped to formulate a general model of
conjunctival scarring (Angella et al., 2000). A unique
aspect of glaucoma filtration surgery healing is the
bathing of wound tissues by aqueous humor. No problem
was viewed about IOP 1 month after the surgery in cats.
Anterior chamber depth was included in the observations
as an indirect indicator of the drainage of fluid through
the tube into the subconjunctival space. In this case, the
anterior chamber was flat on postoperative day 1 and
gradually deepened over the next 7 days.
Experience has shown that intraocular pressure is
not a reliable indicator of filtration surgery (Mead et al.,
2003). Furthermore, in this case IOP was detected below
normal limits in postoperative period. The decrease in
IOP after trabeculectomy is attributed to increased
aqueous outflow through the outflow facility of the
anterior chamber aqueous (Amelinckx et al., 2009).
There was not determined any decreased in IOP after
postoperative period.
In conclusion, trabeculectomy method with raised
scleral flap decreased intraocular pressure in cats with
congenital glaucoma and may proposed for treatment of
congenital glaucoma.
REFERENCES
Amelinckx, A., Castello, M., Arrieta-Quintero, E., Tinthu, L.,
Nelson, S., Eleut, H., Richard, K.L., Sanjoy, K.B., Jean-
Marie, A.P., 2009. Laser trabeculoplasty induces
changes in the trabecular meshwork glycoproteome: a
pilot study. Journal of Proteome Research 8, 3727-
3736.
Angella, G.J., Sherwood, M.B., Balasubramanian, L., Doyle,
J.W., Smith, M.F., Van Setten, G., Goldstein, M.,
Schultz, G.S., 2000. Enhanced short-term plasmid
transfection of filtration surgery tissues. Investigation
of Ophthalmologic Vision Science 41, 4158-4162.
Mead, A.L., Wong, T.T.L., Cordeiro, M.F., Anderson, I.K.,
Khaw, P.T., 2003. Evaluation of anti-TGF- β2 antibody
as a new postoperative anti-scarring agent in glaucoma
surgery. Investigation of Ophthalmologic Vision
Science 44, 3394-3401.
Melo, A.B., Razeghinejad, R., Palejwala, N., Myers, J.S.,
Moster, M.R. Spaeth, G.L., Katz, L.J., 2012. Surgical
repair of leaking filtering blebs using two different
techniques. Journal of Ophthalmic Vision Research 7,
281-288.
Samuelson, D.A., Brooks, D.E., 2011. Small Animal
Ophthalmology. Thieme Medical Publishers, New York.
Tomlinson, C.P., Belcher, C.D.3rd., Simith, P.D., Simmons, R.J.,
1987. Management of leaking filtration blebs. Annual
Ophthalmology 19, 405-411.
Wang, W., Zhou, M., Huang, W., Zhang, X., 2013. Ex-PRESS
implantation versus trabeculectomy in uncontrolled
glaucoma: a meta-analysis. Plos One 2013, 8: e63591.