Dr.Samrat Chatterjee, C07146, Dr. DeepshikhaAgrawal
Dr Samrat Chatterjee, Dr Deepshikha Agrawal
Cornea & Anterior Segment Services, MGM Eye Institute, Raipur.
Email: samrat@mgmeye.org
Similar to cataract, dry eye disease (DED)is widely prevalent in the elderly population. [1]Therefore it is likely that DED may complicate the outcome of cataract surgery. Apart from the overlapping demographics of the two conditions ,other factors which are important arecorneal nerve denervation from the surgical incision, elevation of inflammatory mediators, loss of goblet cells and changes in meibomian gland function. [2]
Several published studies have reported post-operative DED and meibomian gland dysfunction (MGD) in patients without prior history of DED. [3-5]Few studies have observed higher patient comfort and tear film parameters when patients undergoing phacoemulsification (PE) are treated with artificial tears in the postoperative period. [6] But there are also other studies with contrary findings. [7-8]
The purpose of this study was to evaluate various symptoms, tear film parameters and indicators of meibomian gland dysfunction (MGD) in patients without pre-existing DED undergoing routine PE and intra-ocular lens (IOL) implantation and compare the findings with that of the unoperated eye.
Methods
This cross-sectional study was conducted at a tertiary eye care facility in central India over a six month period (October 2015 to March 2016). A sample size calculation based on prevalence data of a previously published study [4] yielded a sample size of 108 patients. The study was approved by the Institute Ethics Committee. The study includedpatients who had undergone PE with IOL in one eye and no history of surgery in the other eye. Exclusion criteria included intra- or post-operative complications, prior DED or ocular surface disease, anatomical abnormalities of the ocular adnexa or anterior segment, ocular infection or inflammation, and long term use of topical or systemic medications associated with dry eye.PE was performed under peribulbar anesthesia through a 3.5 mm superior sclerocorneal tunnel.A stop and chop technique was used in all cases and an acrylic foldable IOL was implanted in the bag. Postoperatively each patient was prescribed topical prednisolone acetate 1% in weekly tapering dose for one month and ofloxacin 0.3% q.i.d. for 2 weeks. No other topical eye drops were prescribed.
One month (+1 week) after surgery when all topical medications had ceased patients underwent visual acuity measurement, refraction, Ocular Surface Disease Index (OSDI) questionnaire, fluorescein tear film break up time (FTBUT), Schirmer 1 test without anesthesia, fluorescein and Lissamine green staining of the cornea and conjunctiva with the Oxford scale. Meibomian gland dysfunction was assessed by 4 lid margin characteristics (telangiectasia, plugging of meibomian gland orifices, lid margin irregularity and anterior or posterior displacement of mucocutaneous junction), meibum quality and meibum expressibility. IOVS Statistical tests used were student t test and Mann Whitney U test for independent samples respectively. All statistical analysis was performed on SPSS for Windows ver. 16.0 and a p value less than 0.05 was considered to be statistically significant.
Results:
This study evaluated 108 eyes of 108 patients who had undergone uneventful PE with IOL implantation and a routine postoperative period. There were 70 (64.8%) males and 38 (35.1%) females. The mean age of the patients were 59.5 ± 9 (range: 23 – 77) years. The right eye was operated in 55 (50.9%) patients and the left eye in 53 (49.1%) patients.
The mean OSDI score was 2.4 ± 4.3 (range: 0 – 17.5). Only 4 (3.7%) patients had a score higher than 15.0.The average tear film stability evaluated by FTBUT and tear production evaluated by Schirmer 1 test between the operated and unoperated eyes did not differ statistically (P= 0.7) and P= 0.62, respectively). Similarly lid margin abnormalities, meibum quality and meibomian gland expression also did not differ significantly between the operated and unoperated eyes (P=0.91, p=0.1 and P=0.95 respectively). There was no clinical evidence of ocular surface damage and staining with fluorescein and lissamine green did not differ between the operated and un-operated eyes (p=0.7 and p=0.8 respectively).
Discussion:
The present study did not find significant ocular symptoms of DED in patients undergoing routine phacoemulsification cataract surgery. Tear film stability, tear production, ocular surface staining or meibomian gland function was not statistically different in the operated eye in comparison to the unoperated eye one month after cataract surgery. These results seem to suggest that cataract surgery does not cause DED or MGD in normal circumstances.
These findings are contrary to what is generally reported in literature. The reason for not detecting signs and symptoms of DED in the present study could be due to either one or all of the following factors: superior sclerocorneal tunnel incision, nonuse of topical NSAIDs in the postoperative period, and timing of evaluation.
The corneal nerves may be injured during cataract surgery. The corneal nerves in the sub-basal plexus has a preferential run from 9 to 3 o’clock direction in the plane between the basal epithelial cells and Bowman’s membrane,[9]and may get injured by a temporal clear corneal incision giving rise to DED.[10] Manual small incision phacoemulsification with a superior incision seems to spare these nerves.[11]The location (superior sclerocorneal) and size (3.5mm)of the incision in the present study may have caused minimal disruption of the sub-basal nerve plexus in the cornea. Topical NSAIDs can lead to corneal toxicity. Although diclofenac has been most commonly implicated, all topical NSAIDs are toxic to the ocular surface epithelium.[12]Some of the studies reporting DED after cataract surgery had used NSAIDs for a prolonged duration in the postoperative period.[3] Few studies have reported increased symptoms and signs in the immediate postoperative period (7-15 days),[4,11] while others have reported return to normalization of the tear film and ocular surface after the first month or even later.[7,8] In the immediate and early postoperative period two factors may confound the various tests used to detect DED – the inflammation from the surgery and the use of topical medications containing preservatives. We evaluated patients after one month when postoperative inflammation had subsided and topical medications had been discontinued.
Therefore it may be safe to conclude that DED after routine PE through superior sclerocorneal tunnel incision in subjects without pre-existing DED may be insignificant and does not warrant the routine empirical use of artificial tears as is suggested in some studies.
References:
1] The epidemiology of dry eye disease: report of the epidemiology subcommittee of the International Dry Eye Workshop (2007). Ocul Surf 2007;5:93-107.
2] Sutu C, Fukuoka H, Afshari NA. Mechanisms and management of dry eye in cataract surgery patients. Curr Opin Ophthalmol 2016; 27:24-30.
3] Li XM, Hu L, Hu J, Wang W. Investigation of dry eye disease and analysis of the pathogenic factors in patients after cataract surgery. Cornea 2007;26:S16-S20.
4] Kasetsuwan N, Satitpitakul V, Changul T, Jariyakosol S. Incidence and pattern of dry eye after cataract surgery. PLoS One 2013;8:1-6.
5] Han KE, Yoon SC, Ahn JM, Nam SM, Stulting RD, Kim EK, et al. Evaluation of Dry Eye and Meibomian Gland Dysfunction. Am J Ophthalmol 2014; 157:1144-50.
6] Sanchez MA, Arriola-Villalobos P, Torralbo-Jimenez P, Giron N, de la Heras B, Vanrell RH, et al. The effect if preservative-free HP-Guar on dry eye after phacoemulsification: a flow cytometric study. Eye 2010;24:1331-7.
7] Venincasa VD, Galor A, Feuer F, Lee DJ, Florez H, Venincasa MJ. Long-term effects of cataract surgery on tear film parameters. ScientificWorldJournal 2013; 2013:643764.
8] Cetinkaya S, Mestan E, Acir NO, Cetinkaya YF, Dadaci Z, Yener HI. The course of dry eye after phacoemulsification surgery. BMC Ophthalmology 2015;15:68.
9] Muller L, Vrensen GFJM, Pels L, Cardozo BN, Willekens B. Architecture of human corneal nerves. Invest Ophthalmol Vis Sci 1997; 38:985-94.
10] Kim JH, Chung JL, Kang SY, Kim SW, Seo KY. Change in corneal sensitivity and corneal nerve after cataract surgery. Cornea 2009;28:S20-S25.
11] Sitampoul R, Sancoyo GS, Hutauruk JA, Gondhowiardjo TD. Sensitivity change in cornea and tear layer due to incision difference on cataract surgery with either manual small incision cataract surgery or phacoemulsification. Cornea 2008;27:s13-s18.
12] Lee J, Kim YH, Park YM. The toxicity of nonsteroidal anti-inflammatory eye drops against human corneal epithelial cells in vitro. J Korean Med Sci 2015;30:1856-64.