Postoperative Complications after Phacoemulsification and Implantation of Foldable Acrylic Intraocular Lenses in Dogs

Cataract surgery in companion animals is considered as an elective procedure with aim to improve the animals’ quality of life. However, despite significant advances in canine cataract surgery over the years, many post-operative complications persist.
       
Most complications that result from lens extraction and affect vision recovery are related to postoperative uveitis. Corneal oedema, aqueous flare, synechiae, capsular opacification, fibro-pupillary membranes, pupillary obstruction, vitreous alterations, ocular hypertension and glaucoma are some of the most important complications (Nasisse and Davidson, 1999). Millichamp et al., (1991) suggested that miosis and flare are complications resulting from intraocular procedures, which prolong postoperative recovery and predispose to the formation of synechiae. Chiurciu et al., (2010) stated that corneal oedema can be caused by lesions to the corneal endothelium during the trans-operative period by irrigation fluid turbulence, air bubbles and/or fragments of the lens dispersed by the ultrasonic energy from the phaco tip. In some cases, the lesion to the endothelium can be permanent, as observed in studies of Guimaraes et al., (2017). Wilkie and Colitz (2007) stated that postoperative intraocular haemorrhage or hyphema after phacoemulsification may be due to severe uveitis, retinal detachment, extreme hypotony, or due to patient activity causing trauma to the eye. Klein et al., (2011) reported that postoperative ocular hypertension (22.9%), corneal lipid opacity (19.0%), uveitis (16.2%), intraocular haemorrhage (12.3%), retinal detachment (8.4%) and glaucoma (6.7%) were the most common postoperative complications seen in eyes.
       
These complications can be transient and unless medically treated may results in discomfort and poor vision recovery in patients. This study evaluated post-operative complications after implantation of different types of foldable acrylic lenses following phacoemulsification procedure.

Clinical cases of dogs presented at Teaching Veterinary Clinical Complex (TVCC) NDVSU, Jabalpur and Madhya Pradesh State Veterinary Hospital, Bhopal during the year 2017-19 with the history and symptoms suggestive of cataract were subjected to detailed physical and hematobiochemical tests to rule out underlying systemicdiseases. Detailed ophthalmological, neuro-ophthalmic and ultrasonographic examination were conducted to confirm the diagnosis and to ascertain the stage of cataract. The dogs (n=24) were selected for surgery after satisfactory outcome of their haematological, systemic and hepatic tests. These 24 dogs were then divided randomly into four groups consisting of six dogs each and only one eye of each dog was subjected to procedure. Owner consent was taken for cooperation and compliance of an uncompromised postoperative follow up till 90 days.
       
The phacoemulsification procedure was performed under general anaesthesia, which was induced by Inj. Atropine Sulphate @ 0.03 mg/kg, Inj. Xylazine @ 1 mg/kg, I/M followed by Inj. Propofol @ 5 mg/kg I/V, along with peribulbar nerve block, using 2% Lignocaine. The phacoemulsification procedure was performed by bimanual method (Gelatt and Gelatt, 2011). After complete aspiration of cataractous lens, square edge hydrophilic IOL were implanted in group I, in group II round edge hydrophilic IOLs were implanted, in group III square edge hydrophobic IOLs implantation was done and in group IV round edge hydrophobic IOLs were implanted. Routine postoperative medications were prescribed for the follow-up period along with application of Elizabeth collar to avoid self-mutilation.
       
The post-operative complications were recorded on 1, 3, 7, 15, 30 and 90 day post procedure. Posterior capsule opacification was evaluated in all the dogs with functional vision on day 15, 30, 60 and 90, postoperatively, by slit lamp bio microscopy.

Gelatt and Gelatt (2011) mentioned that cataract surgery in both human and animal ophthalmology continues to be identified with the specialty and undoubtedly is the most important intraocular surgery performed in the dog. Glover and Constantinescu (1997) noted that the advent of phacoemulsification lens extraction and artificial intraocular lens (IOL) implantation offers a favourable success rate; however, many post-operative complications reduces the success rate of this procedure.
 
Postoperative complications
 
Miosis
 
Postoperative miosis occurred on day 1, postoperatively in 83.33% (n=5/6) eyes of group I, which subsided and persisted only in 33.33% (n=2/6) on day 3, postoperatively. Complete absence of miosis was observed on day 7, 15 and 30, postoperatively. In group-II eyes, occurrence of miosis was recorded as 100% (n=6/6) on day 1. This was significantly (p<0.05) reduced in 33.33% (n=2/6) eyes on day 3. On subsequent postoperative days miosis was not observed in any of the eyes. Group-III revealed presence of miosis in 83.33% (n=5/6) on day 1. On day 3, miosis subsided and observed in 33.33% (n=2/6) eyes. However, on day 7, miosis remained only in 16.66% (n=1/6). After day 7 postoperative, none of the eyes showed miosis. Group-IV showed miosis in 83.33% (n=5/6) eyes on day 1 postoperatively. On day 3 postoperative day, miosis was noted in 50.00% (n=3/6) eyes. From day 7 onwards, miosis was not observed in any of the cases. Findings of this study concurred with findings of Kumar (2008), who reported mild to moderate miosis on day 1 and 3, postoperatively and there after a declining trend on subsequent postoperative days. In the current study, occurrence of postoperative miosis may be attributed to the prolonged duration of phaco-fragmentation procedure as well as IOL implantation, which might have resulted in an intense postoperative iridocyclitis with uncontrollable miosis as suggested by Gelatt and Gelatt (2011). Postoperative miosis was managed by instillation of mydriatic drugs, as prescribed by Gelatt and Wilkie (2011).
 
Aqueous flare
 
The postoperative aqueous flare in group-I was observed on day 1 in 66.66% (n=4/6) eyes. Statistically non-significant increased aqueous flare was observed on day 3 (Fig 1) in 83.33% (n=5/6) eyes. Thereafter, a declining trend ensued, resulting in observation of flare in 50.00% (n=3/6) eyes on day 7, 50.00% (n=3/6) eyes on day 15 (Fig 2) and 16.66% (n=1/6) eyes on day 30 postoperatively. In group-II, aqueous flare on day 1, postoperatively, was found in 66.66% (n=4/6) eyes. Non-significant increased aqueous flare in 83.33% (n=5/6) eyes was recorded on day 3. Thereafter, from day 7, gradual decline was observed in 83.33% (n=5/6) eyes. On day 15 and 30 a reducing trend in aqueous flare was observed in 50.00% (n=3/6) eyes and 33.33% (n=2/6), respectively, which differed significantly (p<0.05) than score on day 3, postoperatively. The data of group-III revealed, incidence of aqueous flare as 66.66% (n=4/6) on day 1, which increased to 100.00% (n=6/6) eyes on day 3, although it differed non significantly. Statistically non-significant decline was observed on day 7 in 50.00%, (n=3/6). Aqueous flare values further declined on day 15 and 30 postoperatively and reduced significantly (p<0.05) than day 3 values. Evaluation of aqueous flare data of group-IV indicated significantly (p<0.05) higher scores on day 1, 3, 7 and 15 compared to scores at day 30, postoperatively. The results of current study are in agreement with Yi et al., (2006), who reported observation of flare up to day 14 and complete absence thereafter. Kalaka et al., (2017) also noticed regression of clinical signs of aqueous flare after 3 to 7 days post-surgery with treatment of topical corticosteroids and antibiotics. Honsho et al., (2007) evaluated aqueous humour transparency and flare and reported that the flare started immediately at the end of the surgical procedures and was moderate to severe in both eyes. Despite pre and postoperative anti-inflammatory therapy, moderate to severe flare was observed, as also encountered in current study. This might be due to the dilatation of vessels in the iris and ciliary body and from an increased permeability of the blood-aqueous barrier mediated, largely, by the release of prostaglandins.
 

 

 
Hyphema
 
In group-I, postoperative hyphema was observed in 33.33% (n=2/6) eyes on day 1 till day 3 and decreased to 00.00% (n=0/6) on day 7 onwards. Similarly, 16.66% (n=1/6) eyes of group-II showed hyphema on day 1 and 3, which later decreased to 00.00% (n=0/6) on day 7. On subsequent observation days, no hyphema was observed in any of the eyes. In group-III, 16.66% (n=1/6) eyes operated showed hyphema on day 1 (Fig 3). On the day 3 observations, none of the eyes showed hyphema and similar results were obtained on subsequent days of observation. Hyphema was observed in 33.33% (n=2/6) eyes on day 1 in group-IV. On day 3 observation 16.66% (n=1/6) eyes showed hyphema. A complete regression of hyphema was observed on day 7 and on subsequent days, it was not observed in any of the eyes. Gelatt and Gelatt (2011) stated that hyphema or blood in the anterior chamber may be an early or late complication of cataract extractions and lensectomy. Klein et al., (2011) also observed hyphema in 22 eyes (12.3%) and reported intraocular haemorrhage occurrence at a median of 10 days (0-513) postoperatively. Current study findings were in agreement with Guimaraes et al., (2017) that reported non-significant difference in the incidence of hyphema between hydrophilic and hydrophobic IOL implanted groups. The cause of postoperative hyphema in the current study was self-inflicted trauma and coinciding uveitis as suggested by Wilkie and Colitz (2007).
 

 
Corneal opacity
 
The postoperative corneal opacity recorded for group-I was moderate to mild with an average score of 1.67±0.21 on day 1 (Fig 4). Complete absence of corneal opacity was observed on Dog 6 from day 7 onwards (Fig 5), in Dog 5 on day 15 onwards and in Dog 2 day 30 onwards, postoperatively. All the other dogs showed moderate to mild progressive corneal opacities, which failed to respond to treatment protocols. All the dogs in group-II exhibited corneal opacity on day 1 day with a score of 1.83±0.17. Statistically non-significant difference was observed on scores of days 1, 3, 7, 15 and 30. However, complete absence of corneal opacity was observed in Dog 1 and Dog 4 on day 7 and in D6 on day 15 onwards, postoperatively. Remaining dogs showed severe to moderate progressive corneal opacities, which failed to respond to treatment protocols. In group-III, corneal opacity scores were 1.50±0.22 with mild to moderate opacity in all the eyes with continuation on day 3. On day 7, Dog 1, Dog 3, Dog 4 and Dog 6 eyes showed absence of corneal opacity, whereas D2 and D5 showed severe corneal opacity with a score of 1.00±0.63. This trend continued and on 15 and 30 postoperative days and non-significant improvement was observed in Dog 2 and Dog 5. Mild to moderate corneal opacity was observed in all the dogs of group-IV with a score of 1.67±0.21. This persisted on day 3 postoperatively. On day 7, diminished corneal opacity was observed in D2, D3 and D6 and severe to moderate corneal opacity was observed in rest of the dogs with score of 1.17±0.54. This trend continued day 15 and 30 postoperative days.
 

 

       
The results and trends observed in this study concurred with findings of Sooryadas (2010), who observed significant reduction of corneal transparency on the first postoperative day which remained so until day 7. Significant gain in the transparency was observed on the day 14 onwards. Ahmad et al., (2017) found that corneal opacity and uveitis were the most common post-operative complication after phacoemulsification It was suggested that trauma caused to the eyes by procedure, could have damaged the corneal endothelium and resulted in severe corneal opacity and corneal oedema. This may also be a reason of corneal opacity in the present study.
 
Posterior capsular opacification
 
None of the dogs showed incidence of PCO up to day 90 of observation. The results are in accordance with Ahmad (2016) who did not find any incidence of PCO after phacoemulsification and IOL implantation. However, earlier workers viz. Kalaka et al., (2017) reported incidence of PCO in 9 (37.5%) out of 24 cases, after 80 days post operatively.

In the current study, statistically non-significant (p≤0.05) variations were found for all the post- operative complications viz. Miosis, aqueous flare, ocular discharge, corneal opacity and hyphema among the groups. However, within the groups initially higher values were recorded and on subsequent days a declining trend of varying degrees were observed due to postoperative protocols.The corneal opacity was a major postoperative complication leading to failure to achieve vision with other coinciding neuro-ophthalmic conditions.It was concluded no significant difference was found in occurrence of postoperative complications among dogs implanted with different IOLs of hydrophilic or hydrophobic material and designs.