This study was carried out with the objective of finding refractive status of patients undergoing phacoemulsification surgery for cataract extraction. Success of cataract surgery can be quantified with the improvement in visual acuity with least amount of refractive error. Prospective study of 44 patients was done pre operatively and with subsequent follow up in the first, third and eighth week post operatively. Pre and post operative evaluation was carried out in terms of visual acuity, refractive error and corneal curvature. Among patients undergoing surgery, 91.0% achieved visual acuity of 6/9 or better at eighth week follow up 73.3% of patients had astigmatism of 1.25 dioptric cylinder or less. Keratometry readings showed insignificant variability in the preoperative and postoperative period (p > 0.05). This confirms that phacoemulsification surgery does not change the corneal curvature significantly and thereby induces less amount of astigmatism

Joshi, MR

Shakya, S

Nepal Medical College Journal

English

Joshi, Mahesh Raj

Plymouth Electronic Archive and Research Library

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/26826654Change in refractive status of the patients undergoing phacoemulsificationsurgeryArticle · March 2009Source: PubMedCITATIONS5READS1512 authors:Some of the authors of this publication are also working on these related projects:Sampling efficiency and internal noise in motion perception in development and ageing View projectPerceptual distortion in Keratoconus View projectMahesh Raj JoshiUniversity of Plymouth22 PUBLICATIONS   99 CITATIONS   SEE PROFILESuraj Shakya-VaidyaBlind Rocks UK31 PUBLICATIONS   400 CITATIONS   SEE PROFILEAll content following this page was uploaded by Mahesh Raj Joshi on 17 May 2014.The user has requested enhancement of the downloaded file.19Change in refractive status of the patients undergoingphacoemulsification surgeryMR Joshi1 and S Shakya21Department of Ophthalmology, Om Hospital and Research Center and 2Department of Ophthalmology,Nepal Medical College Teaching HospitalCorresponding author: Mahesh Raj Joshi, Om Hospital and Research Centre, Chabahil, P. O Box: 13494, Kathmandu, Nepal.e-mail: mahesh_raj@hotmail.comABSTRACTThis study was carried out with the objective of finding refractive status of patients undergoingphacoemulsification surgery for cataract extraction. Success of cataract surgery can be quantified with theimprovement in visual acuity with least amount of refractive error. Prospective study of 44 patients was donepre operatively and with subsequent follow up in the first, third and eighth week post operatively. Pre and postoperative evaluation was carried out in terms of visual acuity, refractive error and corneal curvature. Amongpatients undergoing surgery, 91.0% achieved visual acuity of 6/9 or better at eighth week follow up 73.3% ofpatients had astigmatism of 1.25 dioptric cylinder or less. Keratometry readings showed insignificant variabilityin the preoperative and postoperative period (p>0.05). This confirms that phacoemulsification surgery doesnot change the corneal curvature significantly and thereby induces less amount of astigmatism.Keywords: Phacoemulsification surgery, refractive status, astigmatism, corneal curvature.INTRODUCTIONCataract is the most common cause of blindnessworldwide1- similarly in Nepal, cataract accounts for66.8% of blindness.2 According to research, in thedeveloping world one blind person takes two people outof the work force if the blind requires care of an ableadult.3 So in the developing country like Nepaleconomical consequence of cataract is two fold.Complication of cataract surgery has been one of theleading causes of visual impairment.Phacoemulsification is a safer and reliable surgery forrestoration of visual acuity in patients with cataract, andis superior to extracapsular cataract extraction (ECCE).4The basic advantage of this method over theconventional ECCE is that it involves a very smallincision (3.00mm compared to 8.00-10.00 mm ofECCE), this small incision results in faster woundhealing without need of wound suturing. Studies haveshown that Phacoemulsification procedure produces lessastigmatism and more rapid visual rehabilitation alongwith better quality of life.5-7 If this is so, this procedurecan be very rewarding for Nepalese population as wellto provide best post operative vision without the glasses,where glasses are rarely worn on regular basis and rarelychanged if broken.PATIENTS AND METHODSA prospective study of 44 patients undergoingphacoemulsification surgery for cataract extraction wasconducted. Cases which had preoperative conditions thatcould influence the post operative refractive status, suchas patients who had trabeculectomy, were excluded fromthe study as well as those planned for the combinedsurgical procedure. Among these patients 19 underwentclear corneal incision while 25 scleral tunnel incision.All patients undergoing surgery were evaluated preoperatively. Visual acuity was recorded with the help ofinternally illuminated standard Snellen’s Chart.Biomicroscopy and Direct Ophthalmoscopy was doneto find out the type of cataract and to rule out other ocularpathologies. Streak Retinoscopy was performed in a darkroom and subjective refraction done to find out the best-corrected visual acuity. Keratometry was performed forevery eye, readings were taken in two principalmeridians; three times and the mean of the readings wastaken and recorded.Same evaluations were carried out post operatively inthe first, third and eighth week. The findings wererecorded and data evaluated to come up with final results.RESULTSAmong the 44 patients that underwent surgery 27patients had pre operative vision of less than 6/60, 13had 6/24-6/60 whereas, 4 had vision of 6/18 or better.Among the total patients that underwentphacoemulsification surgery, 19 had clear cornealincisions and 25 had scleral incision.Most of the patients had astigmatism in first week follow upirrespective of type of incision. The mean astigmatism forOriginal Article Nepal Med Coll J 2009; 11(1): 19-2220patients with clear corneal incision was 1.43D (SD 0.89) and1.24 D (SD 1.24) for those with scleral incision with majorityhaving astigmatism of 0.75 to 2.00 dioptres (Table-1).The amount of astigmatism after surgery in post operativeperiod of both third week and eighth week with cornealincision showed mean astigmatism of 0.97D (SD 1.02).Majority of the patients (68.7%) had astigmatism of lessthan 1.25 D. On the other hand 78.6% of patients receivingscleral incision had astigmatism of less than 1.25 D withmean astigmatism being 0.91 D (SD 0.58).Patients undergoing phacoemulsification surgery withclear corneal incision showed decay in astigmatismresulting in 0.00-0.50 D of astigmatism in majority ofcases by third week onwards (Fig. 1). Patients who hadundergone phacoemulsification surgery with scleralincision showed astigmatism of 0.75-1.25 D in majorityof cases even after the third week and later (Fig. 2).Mean preoperative keratometric reading was 7.77mmand 7.64 in vertical meridian and horizontal in thosewith corneal incisions and 7.62mm in both vertical andhorizontal meridians in those receiving scleral incision.Keratometry reading showed changes over the postoperative period with mean radius of curvature for thecorneal incision group being 7.74mm and 7.72mm inthe vertical and horizontal meridian and 7.63mm and7.59mm for scleral group respectively in post operativeperiod of third week and later (Table-2).These changes in the keratometric readings wereinsignificant in both scleral and corneal groups and inboth the meridians, vertical as well as horizontal with pvalue >0.05, using paired t-sample test.Among these patients few were astigmatically neutral(6 in cases of corneal and 2 in cases of scleral) and amongthose with astigmatism, more than 60.0% had againstthe rule astigmatism while equal number of patients hadwith the rule and oblique astigmatism (Fig. 3).Among the forty-four patients that underwent thephacoemulsification surgery, majority recovered the bestcorrected visual acuity of 6/9 or better whereas twopatients had acuity ranging from 6/18 to 6/24. One patientwith Amblyopia had visual acuity of 6/60 (Table-3).DISCUSSIONSThe evaluation of pre operative visual acuity (VA)showed that majority of patients turned out for surgerywhen the available vision was not sufficient for theirdaily activities with 61.4% (n=27) seeking surgery withacuity of less than 6/60.  Population based surveys inNepal, India and China has shown that of all the patientsoperated on for cataract, 21.0-53.0% had a presentingvisual acuity of less than 6/60.8 The mean astigmatismin patients with corneal incision in first week was 1.43DTable-2: Mean keratometric readingsKeratometry Corneal Incision Scleral IncisionReadings Vertical Horizontal Vertical HorizontalMean (SD) Mean (SD) Mean (SD) Mean (SD)Pre-Op 7.77 (0.35) 7.643 (0.13) 7.62 (0.29) 7.622 (0.23)First Week 7.70 (0.30) 7.71 (0.22) 7.59 (0.31) 7.633 (0.27)Third Week and later 7.74 (0.25) 7.72 (0.20) 7.63 (0.27) 7.59 (0.22)* P> 0.05Table-1: Showing astigmatism in the first week follow upAmount of Astigmatism (Diopters) Corneal Scleral0.00-0.50 4 60.75-1.25 5 111.50-2.00 8 52.25-3.00 1 1>3.00 1 2Total 19 25Nepal Medical College JournalFig. 1. Astigmatism in first week and third week and later (Corneal incision)21(+/-0.89) and 1.24 D (+/-1.24) in those with scleralincision. In subsequent follow up, little change in theaxis of astigmatism was noted. The amount ofastigmatism however showed gradual change over aperiod of time in most of the cases. At the end of thirdweek and eighth week, corneal incision had meanastigmatism of 0.97D (+/- 1.02) and in scleral incisiongroup the mean astigmatism was 0.91 D (+/- 0.58).In a study done by R. Sapkota in patients undergoingthe surgery with the conventional ECCE reported upto1.00 D of cylinder in 58.3% of patients, 25.0% with morethan 2.00D of cylinder and 16.7% with more than 5.00Dof cylinder.9 While in our study only 18.2% of thoseundergoing phacoemulsification surgery reportedastigmatism of more than 1.50 D at the end of eightweek and none had astigmatism of more than 3.00 D.Dam-Johansen M, Olsen T et al evaluated the refractiveresults after phacoemulsification and ECCE, reportedthe mean surgically induced astigmatism to be 0.91Dand 1.36D in the phacoemulsification and extracapsularcataract extraction group. And concluded thatphacoemulsification improves the surgical control ofrefractive outcome of cataract surgery.10 Similarly inanother study by Watson A and Sunderraj P has reportedthat less astigmatism was induced byphacoemulsification than extracapsular surgery,measured at all post-operative time intervals.6The results of this study shows that there is no significantdifference in amount of astigmatism between bothgroups receiving the corneal and scleral incisionthroughout the study period with both showing 1.25Dof mean astigmatism at the end of follow up. Similarresults have been reported by the different researchers;Poort-van Nouhuijs HM, Hendrickx KH reported nosignificant difference in patients receiving scleral tunnelTable-3: Best corrected post operativevisual acuity (Final Evaluation)Visual Acuity No. Of Patients6/6-6/9 40 (91.0%)6/12-6/18 2 (4.5%)6/24-6/60 2 (4.5%)Total 44MR Joshi et alFig. 3. Type of astigmatismFig. 2. Astigmatism in first week and third week and later (Scleral incision)22incision and clear corneal incision.11 Similarly Gross RH,Miller KM found astigmatism to be of same amount inboth group after 6 weeks.12The change in Keratometry reading in both groupshowed insignificant change in corneal curvature.Similarly topographic studies following cataract surgeryby phacoemulsification has demonstrated that a smallerwound in phacoemulsification surgery produces minimalchange in corneal curvature.13 This consolidates the resultof minimum change in astigmatism due to thephacoemulsification surgery.Patients were willing to undergo surgery only whenavailable vision was hindering their day to day activities.Most of the patients undergoing phacoemulsificationsurgery achieved normal visual acuity with majorityhaving only a small postoperative astigmatism.Phacoemulsification surgery hence ensures a normalvisual recovery with insignificant change in cornealcurvature and a few patients require spectacles aftersurgery.ACKNOWLEDGEMENTSWe would like to extend our heartfelt gratitude to all the staffmembers of B P Koirala Lions Centre for Ophthalmic Studiesfor all the help rendered to us during this research work. Weare also thankful to Mr. Amrit Pandit, MPH for his help indata analysis.REFERENCES1. World Health Organization (WHO): Program for preventionof Blindness. Report of consultation on the use of Intra OcularLenses in Cataract surgery in the developing countries. WHO/PBL/91-1, Geneva, Dec 3-7, 1990.2. Brilliant GE, Pokhrel RP, Grasset NC et al. The Epidemiologyof Blindness in Nepal: Report of 1981 Nepal BlindnessSurvey. Chelsea, MI: The Seva Foundation. 1988.3. American Academy of Ophthalmology. Epidemiology ofCataracts and Global Perspective. Lens and Cataract, Section11, 64. 1996-97.4. Cheng JW, Wei RL, Li Y. Effect of phacoemulsification versusextracapsular extraction on visual acuity: a meta-analysis.Zhonghua Yan Ke Za Zhi 2004; 40: 474-7.5. Cavallini GM, Lugli N, Campi L, Lazzerini A, Longanesi L.,Surgically induced astigmatism after manual extracapsularcataract extraction or after phacoemulsification procedure.Eur J Ophthalmol 1996; 6: 257-63.6. Watson A, Sunderraj P., Comparison of small-incisionphacoemulsification with standard extracapsular cataractsurgery: post-operative astigmatism and visual recovery. Eye1992; 6 (Pt 6): 626-9.7. Liu JW, Xu JJ, He MG. Comparing patients’ quality of lifeafter phacoemulsification with intraocular lens implantationwith that after extracapsular cataract extraction withintraocular lens implantation. Zhonghua Yan Ke Za Zhi2003; 39: 94-7.8. Dandona L, Limburg H. What do we mean by cataractoutcomes? J Comm Eye Health 2000; 13: 35-6.9. Sapkota RP. Evaluation of refractive status of post operativecataract cases done at BPKLCOS. Unpublished Thesis work.B. P. Koirala Lions Centre for Ophthalmic Studies, TribhuvanUniversity, Kathmandu. 2001.10. Dam-Johansen M, Olsen. Refractive results afterphacoemulsification and ECCE. A comparative study. ActaOphthalmol (Copenh) 1993; 71: 382-7.11. Poort-van Nouhuijs HM, Hendrickx KH, van Marle WF,Boesten I, Beekhuis WH. Corneal astigmatism after clearcorneal and corneo-scleral incisions for cataract surgery. JCataract Refract Surg 1997; 23: 758-60.12. Gross RH, Miller KM. Corneal astigmatism afterphacoemulsification and lens implantation through unsuturedscleral and corneal tunnel incisions.  Amer J Ophthalmol1996; 121: 57-64.13. Hayashi K, Nakao F, Hayashi F. Topographic analysis of earlychanges in corneal astigmatism after cataract surgery. JCataract Refract Surg 1993; 19: 43-7.Nepal Medical College JournalView publication stats

Change in refractive status of the patients undergoing phacoemulsification surgery.

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Change in refractive status of the patients undergoing phacoemulsification surgery.

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