OUTCOME OF PAEDIATRIC CATARACT SURGERY AT TILGANGA INSTITUTE OF OPHTHALMOLOGY , NEPAL

A hospital based prospec ve, observa onal study taking 42 pa ents (77 eyes) aged ≦15 years diagnosed with paediatric cataract were enrolled during a period of 1 year ( Jan 2011 Jan 2012) at Tilganga Ins tute of Ophthalmology, Kathmandu, Nepal. The pa ents underwent either: a) Lens aspira on + Primary posterior capsulotomy (PPC) + Anterior Vitrectomy; b) Lens aspira on + PPC+ Anterior Vitrectomy + Intra-ocular lens (IOL); c) Lens Aspira on + IOL. Post-opera vely op cal ± amblyopia correc on. Sta s cal analysis was carried out by using STATA 9.0. The associa on of changes in the vision of eyes before and a er surgery was analyzed by using generaliza on of McNemar's test (Stuart-Maxwell test). A pvalue of < 0.05 was considered for the sta s cal significance. Ins tu onal Ethics Board approval was obtained from the ins tu onal review commi ee (IRC) of Na onal Academy Medical Sciences ( NAMS ).


INTRODUCTION
"Childhood blindness" describes a number of diseases and 1 condi ons that occur in childhood and early adolescence.It has been es mated that there are 1.4 million blind children in the world, 1 million of whom live in Asia and 2 300000 in Africa.Paediatric cataract is the leading cause of childhood blindness in developing countries .
Early detec on and advanced surgical techniques have improved the prognosis of paediatric cataract in developed countriesbut because of the lack of advanced technology, paediatric cataract and aphakia are s ll a major cause of [3][4][5] childhood blindness in developing world.
In countries like Nepal, a significant barrier to effec ve cataract surgery has been a lack of equipment, shortage of trained paediatric ophthalmologists and anaesthesiologists and the expense of advanced monitoring equipment due to which proper management of paediatric cataract is a 6,7 serious challenge in Nepal.Thus to improve mely eye care of children, evidence-based informa on is very crucial especially when informa on regarding paediatric cataract in nepal are few and sketchy.Tilganga Ins tute of Ophthalmology ( TIO ) is one of the very few ins tu ons in Nepal where paediatric cataract surgery is performed rou nely under general anesthesia.In a way TIO has become a sort of referral centre, a representa ve of the country as a whole in terms of variety of ocular condi ons.Thus this study was carried out to iden fy the visual outcome of childhood cataract surgery in a ter ary eye care centre in Nepal.

METHODOLOGY
This was a hospital based prospec ve, observa onal study done at Tilganga Ins tute of Ophthalmology, Kathmandu from Jan 2011 to Jan 2012.The pa ents were followed up for 6 months following surgery or ll last follow up whichever was more.A total of 42 pa ents (77 eyes) were recruited for the study.All pa ents ≤ 15 years diagnosed with paediatric cataract between 2011 to Jan 2012 were included in the study.Pa ents with trauma c cataract, complicated cataract, pa ents undergoing secondary IOL implanta on were excluded from the study.Ins tu onal Review Commi ee approval was obtained from Na onal Academy Medical Sciences ( NAMS ).
A standard protocol for evalua on of children with cataract was followed.A detailed history was taken from the parents/guardian comprising of chief complaint, age of presenta on, history of trauma, drug use, ante-natal/ peri-natal history, systemic history, developmental milestone, immuniza on history, and any relevant family history.
Pre and Post-op best corrected visual acuity(VA) of each eye were examined using age appropriate tests ; For 0-3 yrs: CSM (Centre Steady Maintain) , Preferen al looking { Cardiff card, Teller Acuity} ; for 3-5 yrs: Light House symbols chart , Sheridan-Gardiner test and for age group >5 yrs, Snellen's E chart were used.
Anterior segment examina on and type of cataract was determined by using slit lamp bio-microscopy/ Kowa SL-15 portable handheld slit lamp or opera ng microscope under general anaesthesia.Fundus status was evaluated with indirect ophthalmoscope, using +20 D Volk lens or +90 D lens a er dilata on with 1% tropicamide.Cycloplegic refrac on was done whenever required.B-scan ultrasonography was done in cases of hazy media opacity obscuring the posterior view.
A detail pre-anaesthe c check up was done by qualified anaesthesiologist.All the surgeries were performed by two highly qualified paediatric ophthalmologists under general anaesthesia (GA).Informed consent was obtained for all pa ents from the parents/gaurdian a er discussion of the risks, benefits and postopera ve care.
The standard paediatric cataract surgery followed: In older children, a er applying bridle suture, superior scleral tunnel was made, lens aspirated and IOL implanted through the tunnel.The tunnel was then closed water ght with 8 0 vicryl.At the end of the procedure, all eyes received a subconjunc val injec on of gentamicin and dexamethasone.
The eye was patched and shield was placed over the eye.
Children with bilateral congenital cataract underwent surgery for the second eye preferably within 1 week of surgery of the first eye.IOP was measured under GA when required using hand held Perkins tonometer .Either, Polymethylmethacrylate (PMMA) lens or foldable lens, manufactured at the Tilganga Ins tute of Ophthalmology (TIO) Fred Hollows IOL factory, were implanted via scleral tunnel or clear corneal incisions respec vely.Any intra-opera ve complica ons whatsoever were recorded in the OT note by the opera ng surgeon or the assistant.Postopera vely, all eyes are given combina on of topical steroids and an bio cs (predacetate / dexamethasone and ofloxacin/chloramphenicol) every 1 hourly for the first week then tapered accordingly depending on the inflammatory status of the eye.Pa ents were examined 1 day, 1 week, 2 weeks, 6weeks, 3 months and 6 months postopera vely.
In every visit, a detailed examina on of the anterior and posterior segment and the possible complica ons were evaluated.VA was assessed using standard protocol described above at each follow up.Pa ents were provided with op cal correc ons for any residual refrac ve errors 6 weeks a er surgery.Likewise amblyopia management was done aggressively by either patching or atropiniza on.If a pa ent was lost to follow up, his or her last recorded vision, and examina on findings were taken as the final postopera ve data.The major outcome measure was final best corrected visual acuity (BCVA).Likewise, the various modes of presenta on, age of presenta on, morphology of cataract, types of surgeries performed, complica ons, need of op cal correc on, amblyopia management were also evaluated.Postopera vely, the refrac ve status of the children was assessed by re noscopy at 6 weeks a er surgery and repeated therea er at each visit therea er.Near glasses were prescribed whenever required.Sta s cal analysis was carried out using STATA 9.0.The associa on of different types of surgery with vision of eyes a er surgery has been assessed by using Chi-square/ Fisher's exact test wherever applicable.Similarly, the associa on of changes in the vision of eyes before surgery and a er surgery has been analyzed by using generaliza on of McNemar's test (Stuart-Maxwell test).A p-value of < 0.05 is considered for the sta s cal significance.

RESULTS
A total of 42 pa ents (77 eyes) were recruited for the study of which 10 eyes were lost to follow up of which 67 eyes completed the study.Seven (17%) pa ents had unilateral and 35 (83%) pa ents had bilateral cataract.

DISCUSSION
Paediatric cataract surgery is only the first stage of a long, o en complex rehabilita on process.Moreover, the cataract surgery itself is a specialized surgery requiring mul disciplinary approach involving anaesthesiologist, paediatrician, qualified paediatric ophthalmologist and optometrist.
The mean age of surgery in the current study was 4.46 years with SD ±4.32 range (0.04 -12) years; median 3 years .This is delayed.As such, in the developed world, most childhood cataracts are diagnosed immediately following birth or even prenatally but late presenta on, especially for congenital cataracts, is a ma er of concern for developing countries , the main reason for late presenta on being lack of awareness and poor socio-economic status.There was an almost equal distribu on of males (52%) and females (48%) in this study.Indirectly it points out that girl child is given equal preference like male child even in developing countries like Nepal as well.There are reports from African/Asian countries regarding gender inequality in paediatric cataract surgery.The Danish study also shows 13 rate of cataract surgery higher in boys than girls.In this study, a total of 83% of pa ents had bilateral presenta on and only 27 % had unilateral cataract.Increased ra o of bilateral cataract has been observed by other researches as 14 well, a ra o of 3:1 reported by Johar et al.Interes ngly a similar study done at TIO by Thakur et al showed 27 pa ents (31.8%) had bilateral cataract and 58 (68.2%), unilateral cataract, the possible reason might be due to inclusion of 6 trauma c cataracts , which are most of the me unilateral.The commonest symptom of presenta on in this study was white pupillary reflex (54%) as has been reported by the 13,15 Danish study and Shrestha UD.Interes ngly nystagmus was in very few cases(1%) and strabismus only in 6%.Wilson et al have reported pre-op nystagmus 29.5% and pre-op strabismus 28%, so compared to that study, 1% is very less which is a good sign because a posi ve nystagmus 16 is a poor predic ve sign of poorer outcome.In this study, the most common type of cataract was total (32%) followed by lamellar (31%).Wilson et al also showed total cataract 16 (68.5%)as the most common morphological variant.Similar repor ng was done (50% total cataract ) in a study carried out in Nepal at TIO by Thakur et aland P. Gogate et al 6,17 (39 % ) in his study.However, studies done in Denmark has shown Nuclear cataract (36%) as the most common 13 morphological variant.This might be one of the reason for late presenta on in developing countries like ours i.e unless the cataract is fully mature and white, it goes undetected.A considerable number of pa ents (56% eyes) in this study presented within 6 months of onset of symptoms.This is be er than what has been reported in the other studies.A study done in West India by P. Gogate et al shows delay of 17 up to 11 years.Delay in presenta on has been a major issue for poor outcome in studies carried out within Nepal 12, 15, 16, 18-20 and outside.
Unfortunately there is a large me lag between many children developing cataract and actually 20,21 presen ng for cataract surgery.
The percentage of visually impaired is quiet high in this study (44%), likewise in non-verbal group a considerable percentage (22%) present with poor fixa on and follow.This corresponds well with 21 findings from other studies.Khandekar et al found the best corrected presen ng vision is <3/60 in (37.9%) of eyes ; P. Gogate et al found pre-opera ve best corrected vision 17 was <3/60 in (76.6%) eyes.Moreover recording visual acuity in children is a big challenge in young children.Inability to record visual status has been men oned in 22,23 other publica ons as well.In this study, the status of the visual acuity was difficult to assess in pre-verbal eyes of children below five years of age so had to resort to nonquan ta ve methods such as preferen al looking method.
The low vision in this study has been seen more in the older age group ; visual acuity < 3/60 in 55% of age group (11)(12)(13)(14)(15) years and in 50% of age group (6)(7)(8)(9)(10) years.This collaborates with similar finding from other studies.Study done by P. Gogate et al has shown preopera ve best corrected vision 17 was poorer for eyes with delayed presen ng cataracts.All the surgeries in this study were carried under GA.A trained anaesthesiologist is available at TIO on regular basis and most of the paediatric surgeries were performed under GA.However, the problem of availability of general anaesthesia is s ll prevalent in many developing countries including Nepal.Opera ng on pa ents in rural se ngs with limited medical facili es and support leads to differences in how these cataracts are managed compared with accepted clinical approaches in the developed world.In this study primary IOL was inserted in 60% of eyes.Cases where IOL was inserted included all eyes more than 2 years old and unilateral cases of any age.Rest of 40% of eyes were planned for secondary IOL, once the child a ained 2 years of age.In recent years primary IOL implanta on is fast becoming the preferred modality of treatment for most children.The visual results in this study are encouraging.Nearly every pa ent in the current study showed improved visual acuity a er surgery.
At the end of 6 months follow up, 74% of eyes had best corrected vision in the range (6/6-6/18) and 86% had good preferen al fixa on.The propor on with good acuity a er surgery is be er than the figures of 44% reported by Yorston et al in Kenya, 48% by Yang et al in Taiwan and 44% by Bas The result is comparable to that reported from series of similarly aged children from developed countries where propor ons achieving 20/60 or be er ranged from [26][27][28][29] 72% to 91%.
In our study, pre-surgery, 53% eyes were blind whereas post surgery, 17% were blind.The 17% classified in the blind group also had improved vision with a good anatomical outcome in comparison to the pre-surgery vision.These were mostly unilateral cases with strabismus.Poor improvement in vision could be due to amblyopia.Amblyopia management was done in 7(9%) eyes.Both op cal correc on and (4-6) hours patching was done for amblyopia management.Of the 7 eyes, 5 were cases of unilateral cataract.It was very difficult to compare the visual outcome between unilateral vs bilateral cases from this study due to less no of sample size; there were only 7 unilateral cases in the current study.The reasons for quan ta ve acuity data being available in only approximately 47% of children are the use of non-quan ta ve methods in younger and noncoopera ve pa ents.This problem of assessing vision in very young and uncoopera ve children [29][30][31] was seen in previous studies as well.
Overall, post surgery there was sta s cally significant improvement in vision in all the eyes.Post-opera ve complica ons associated with paediatric cataract surgery con nue to be a major concern.The risk of post-opera ve complica ons is higher due to greater Gurung RL et al inflammatory response a er paediatric cataract surgery.However, the frequency of post-opera ve complica ons were very less in this study ll the 6 months follow up.Apart from one case of dislocated IOL in vitreous, no other serious complica ons were noted in this study.Visual axis opacifica on ( VAO) , seen in 26 % of the total eyes (n=77) , was the most common post-opera ve complica on seen, but ll the 6 month follow up, none of the eyes required any interven on (Yag-capsulotomy or Surgical interven on ) for the opacifica on .

CONCLUSION
Timely management of paediatric cataract is very challenging in countries like Nepal.A sta s cally significant improvement in vision with minimal post-opera ve complica ons was seen in this study.This study demonstrates that good results can be obtained in developing countries like Nepal also.

RECOMMENDATION
More number of eyes need to be included in the study in order to make a comparison between primary vs secondary implanta on of IOL and to make a comparison between unilateral and bilateral cataract cases.

LIMITATIONS OF STUDY
The assessment of visual acuity in children was very difficult especially in pre-verbal children.Moreover, the results in this study are drawn a er a follow up period of only 6 months.This limits the precision of the study and our ability to draw meaningful conclusions.

Table 1 :
Presen ng Best Corrected Visual Acuity ( n= 77 ) (1%) eyes.Most of the pa ents 41 (56%) eyes presented within 6 months of symptom, however 9 (7%) eyes had late presenta on a er 5 years of onset of symptom.Most of the pa ents were in the visually impaired group < 6/18 (Table1) .In pa ents in whom vision could be assessed only by fixa on method, a significant percentage 17 (22%) eyes were in the poor fixa on group.Excluding the Fix and follow group, 53% (19 of 36) were blind.

Presen ng BCVA Frequency (eyes) Percent
Most of the eyes 40(64%) underwent (Lens Aspira on + Primary Posterior Capsulotomy + Anterior Vitrectomy) followed by (Lens Aspira on + Primary Posterior Capsulotomy + Anterior vitrectomy + Intraocular lens implanta on) in 20 (25%) and (Lens Aspira on + Intraocular Lens) in 17(11%) eyes.IOL was inserted in all bilateral cases aged 2 years and above.All unilateral cases irrespec ve of age were implanted with IOL.Except in 2 cases, IOL was kept in the bag.There was sta s cally significant improvement in BCVA post surgery in all vision group, p <0.0001 (Table2) .

Table 3 :
Pre-opera ve and post-opera ve BCVA (In eyes where quan ta ve VA possible / n= 31 ) week, 7(9%) on 6 week, 14(18%) on 3 month and 20(26%) at 6 month follow up.None of the VAO required immediate interven on.Only one eye had Intra-oclular lens disloca on in the vitreous cavity on first post opera ve day for which immediate vitrectomy was done and the Intraocular lens implanted in sulcus.The final visual acuity in this eye was 6/9.Likewise, one eye (1.29%) had decentered IOL but it required no interven on.Pupillary capture was