Dr. Debdulal Chakraborty,
C10922, Dr. Saptorshi Majumdar, Dr. Samar Kumar
Basak
Presenting author : Dr Debdulal Chakraborty
Co Authors: Dr Samar Basak
Dr Saptorshi Majumdar
Synopsis:
India with 1.2 billion people, has hospitals where ophthalmologists screen large number of cataract patients, with chance of the macular pathology being missed during preoperative evaluation, leading to error of judgment regarding the post operative visual outcome. This pilot study determines if compulsory Spectral Domain Optical coherence tomography (SD OCT) of macula can minimise post-operative surprises.
Methods: 5120 consecutive patients over a six month period who were adviced cataract surgery were taken up for SD OCT imaging of the macula
Results: 18.3% patients had OCT abnormalities missed by ophthalmologists. Decreased macular thickness 6.13%, posterior vitreous detachment in 3.69% vitreomacular adhesion 3.6% cellophane membrane2.48% disruption of the external limiting membrane 1.66%, RPE abnormalities 1.62% irregularities in IS/OS junction in 1.54% and lamellar macular hole 1.13%.
Conclusion: It is a good idea to screen patients with OCT to avoid post-op surprises
Introduction :
India is a country with a population of more than 1.2 billion. As such the hospitals especially the tertiary care ones are very crowded. The ophthalmologist manning these hospitals are hard pressed for time and have to see a large number of patients. Cataract is still the number one cause of visual impairment in the country. In a high volume tertiary care hospital, where a consultant has to dispose a very high number of out patient cases, there are chances of the macular area being inadequately evaluated by slit lamp biomicroscopy using a 90 D lens, during preoperative evaluation of cataract cases, leading to error of judgement regarding the post operative visual outcome. This may mislead the clinician towards unwise clinical decisions1. We evaluate in this pilot study how compulsory Spectral Domain Optical coherence tomography (SD OCT) of the macula can help minimise post-operative surprises and help in prognosticating these cataract patients.
Methods:
Methods: 5120 consecutive patients over a six month period who were adviced cataract surgery were taken up for SD OCT imaging of the macula. This was a prospective, non-comparative cohort from day-to-day general ophthalmology OPD clinic of a Tertiary Eye Hospital, Eastern India.
All patients were evaluated with SD-OCT (RTVue, Optovue, CA, USA) by a trained technician, using a 6 X 6 mm central cube with 128 horrizontal scans passing through the macula. Patients prior to SD OCT evaluation underwent complete evaluation of the eye including visual assessment, slit lamp examination, intraocular pressure measurement, angle evaluation where Von Herrick’s grading was grade II or less, fundus examination, preoperative biometry and SD OCT of the macula. A normal SD OCT of the macula was defined as one having a normal foveal contour with a normal sensory retinal pattern at the fovea, a normal external limiting membrane, a regular inner/outer photoreceptor junction, retinal pigment epithelium choriocapillary complex and a central foveal thickness between 225 to 265u.
Results: There were statistically proportionate number of males and females. Age group was from 45- 65 yrs. A total of 56,268 patients were examined by 8 general ophthalmologists, in 6 months (Jul – Dec,2015) – average being 78.4 patients/day/consultant at 8 hours/day. During clinical examintion there were 874(17.10%) patients were detected with retinal pathology which needed retinal assessment and treatment by a retina specialist and were referred.
Of the remaining 4244 patients there were 217(4.23%) patients who had advanced cataract which did not allow retinal examination and SDOCT. These patients were evaluated with Ultrasonography Bscan for posterior segment status. Out of the rest 4027 patients 941 (18.3%) patients had OCT abnormalities. These were decreased macular thickness in 314(6.13%) patients, evolving posterior vitreous detachment in 189(3.69%) patients, vitreomacular adhesion in 184(3.6%) patients , cellophane membrane in 127(2.48%) patients, disruption of the external limiting membrane in 85(1.66%) patients, RPE abnormalities in 83(1.62%) patients, irregularities in IS/OS junction in 79(1.54%) patients, and lamellar macular hole in 58(1.13%) patients, some of these patients had combined pathology.
Total cases 5120 , 874 were detected retinal pathology , so remaining 5120 – 874 = 4246 , which is not co-relating with figure 4244 , hence 4027 is also not co-relating
Discussion
Discussion
In India cataract is still the no 1 cause of visual loss. With the ever increasing population of our country, the out patient departments are more often than not teeming with patients. As such chances of missing small macular details during biomicroscopic or direct ophthalmoscopic examination are there. OCT exams as part of the routine preoperative tests for cataract surgery is becoming a necessity given the increasing demand for better results. Itis non-invasivein nature and has greater accuracy in the diagnosis of macular diseases1.
Additionally, as OCT becomes more popular and more available, it will subsequently become less costly. Compared to other tests used for the diagnosis of macular diseases, such as retinal angiography, OCT is not only safer, it is more precise and practical.
This is the a pilot study where a very large sample of eyes scheduled to undergo cataract surgery were taken up for OCT evaluation. Previous studies1showed, on pre-operative SD-OCT, occult macular pathology was 13% of eyes, led by AMD (6%), ERM (4%), ischemic maculopathy (2%), and edema (1%). Our study detected hidden macular pathology in 18.3% which could not be picked up clinically by the consultants in busy OPD-clinics. Some of the eyes had serious combined pathology and have implication in adverse postoperative visual outcomes
The difference observed between clinical examination and OCT may be due to the inaccuracy of the pre-op BIO examination performed by the general ophthalmologist, who is not a retinal specialist and may not have noticed the subtle macular changes, especially when lens opacification is present, in the setting of high volume of patients. To ensure that all cataract surgeries will have a preoperative evaluation by a retina specialist is also not practically possible due to the limited number of retina specialist available. Moreira CA et al1showed – OCT diagnosed preoperative maculopathies in 21.4% of eyes, and was more effective than clinicalexamination (11.2%). In our study this figure of Oct diagnosed abnormalities was 18.3%.
Table I: OCT abnormalities
| Macular OCT abnormalities | No | % |
| Decreased macular thickness | 314 | 6.13% |
| Posterior Vitreous Detachment (PVD) | 189 | 3.70% |
| Vitreomacular traction (VMT) | 134 | 2.61% |
| Cellophane maculopathy (ERM) | 127 | 2.48% |
| Irregularities in IS-OS junction | 79 | 1.54% |
| Diabetic macular edema (DME) | 59 | 1.15% |
| Lamellar macular Hole | 58 | 1.13% |
| Choroidal neovascularisation | 47 | 0.90% |
| Miscellaneous | 27 | 0.50% |
Further, even if all cases were seen by retina specialists even then there would still be chance missing of subtle retinal pathology. Therefore, the findings presented here may be very similar to what happens in the real world of ophthalmic practice. These findings may have adverse effect on the visual performanceand also, cataract surgery has the potential to furtherinduce inflammatory and mechanical changes in vitreoretinal structures2.
Early AMDis often missed on clinical examination andso the importance of a preoperative OCT exam is even more evident for patients undergoing cataract surgery.
In 2012, Monestamet al3 showed that patients with clinical signs of AMD at the time of cataract surgery have a lower gain in vision than patients without AMD symptoms.
It was noted that chances of missing out of lesions correlated with the image quality in OCT, i.e. patients whose findings were missed in biomicroscopic examination, had images which were of poorer quality than other images. This was statistically significant(P<0.001). These were the patients with dense cataract making visibility of the macula difficult. This poor visualization may mislead the clinician towards unwise clinical decisions.
Conclusion:
The SD OCT as non invasive method of screening of the macula is well established. Numerous studies have confirmed the utility of evaluation of the macula with SD OCT for prognostication and treatment of unexplained visual loss1-4. In a high volume OPD where small macular details can be missed out it is a good idea to screen all patients with SD OCT to avoid surprises in post operative visual acuity. The patients who were diagnosed clinically to have some macular pathology were sent to the retina clinic for further evaluation and necessary treatment. This pilot study only confirms the fact that all macular pathology cannot be detected by the human eye. These findings may be an eye opener in all patients where cataract surgery is being contemplated and can help the operating surgeon to avoid any pitfalls and surprises postoperatively
Reference:
1.Moreira Ne CA, Moreira Jr CA, Moreira AT. OCT in patients undergoing cataract surgery. Arq Bras Oftalmol.2015;78:241-5.
2.Giansanti G, Bitossi A, Giacomelli G, Virgili G, Pieretti G, Giuntoli M, et al. Evaluation of macular thickness after uncomplicated cataract surgery using opyical coherence tomography. Eur J Ophthalmol. 2013;23(5):751-6.,
3.Monestam E, Lundgvist B. Long-term visual outcome after cataract surgery: Comparision of healthy eyes and eyes with age related macular degeneration. J Cataract Refract Surg. 2012;38(3):409-11
4.Dupps WJ: Preoperative screening for occult disease in cataract surgery candidates. J Cat Refract Surg.2016;42:513-4.