A Clinical Evaluation of OCT proven Macular Edema in Post ...ijhbr.com/pdf/October 2017...

International J. of Healthcare and Biomedical Research, Volume: 06, Issue: 01, October 2017, 49-57

www.ijhbr.com ISSN: 2319-7072

49

Original article:

A Clinical Evaluation of OCT proven Macular Edema in Post operative

Cataract patients operated by Conventional ECCE and SICS techniques

*Dr. Nikhil Balakrishnan, **Dr. KishorBadhe

*Resident, ** Professor, Department of Ophthalmology

Rural Medical College, Pravara Institute of Medical Sceiences ,Loni ( DU) , Maharashtra , India

Corresponding author: Dr. Nikhil Balakrishnan

Abstract

Introduction: Various types of Cataract Surgeries have evolved over the years, of which the three types of Extra Capsular

Cataract Extraction (ECCE) namely Conventional ECCE, Small Incision Cataract Surgery (SICS) and Phacoemulsification are

routinely performed.Cystoid macular edema (CME) following cataract surgery, also known as Irvine-Gass syndrome, is an

important differential diagnosis of painless suboptimal vision following uneventful cataract extraction. The diagnosis of CME

was previously made with fluorescein angiography, after the patient became symptomatic. However, the emergence of Optical

coherence tomography (OCT) has provided a quick and noninvasive means of diagnosis.

In this study we determine the incidence of OCT proven Macular Edema in post operativecataract patients operated by

Conventional ECCE and SICS techniques.

Materials and Methods

100 cases of Post operative Cataract, 50 operated by the Conventional ECCE method and 50 by the SICS technique were

evaluated by OCT at 1 month follow up to examine for the presence of Pseudophakic Cystoid Macular Edema (PCME).

Results : Of the 100 cases studied,13 showed presence of PCME, 8 of whom were operated by the Conventional ECCE method

and 5 by SICS method.

Conclusions : SICS was found to be a superior technique than Conventional ECCE for Cataract surgery in terms of development

of PCME. OCT is an excellent non-invasive tool for macular thickness measurement, which can be used in routine practice for

greater diagnostic accuracy in PCME.

Key Words: Cataract, Conventional Extra Capsular Cataract Extraction(ECCE), SICS, Post Cataract Macular Edema (PCME),

Optical Coherence Tomography (OCT)

Introduction

Cataracts are the major cause of blindness and visual

impairment in developing countries and contributes

to more than 90% of the total disability adjusted life

years.1 Various types of Cataract Surgeries have

evolved over the years, of which Extra Capsular

Cataract Extraction (ECCE) has gained popularity as

it involves retention of Posterior Capsular support for

Intra Ocular Lens (IOL) implantation. Three types of

ECCE surgeries namely Conventional ECCE, Small

Incision Cataract Surgery (SICS) and

Phacoemulsification are routinely performed.2

Conventional ECCE is an open sky procedure which

requires closure of the wound with sutures. SICS is a

self-sealing, sutureless small incision surgery.

Phacoemulsification consists of an even smaller

incision, which is also self-sealing, but is machine

dependent.

SICS is precise, effective and less time consuming

without maintenance demand of equipments3. Also it

has been proved safe and effective in all types and

grades of cataract.

It has been observed that SICS gives lesser post-

operative astigmatism and better postoperative visual



50

outcome, comfort and faster rehabilitation than the

conventional ECCE technique4 and it gives nearly the

similar outcome as that of Phacoemulsification.5

Cystoid macular edema (CME) following cataract

surgery, also known as Irvine-Gass syndrome, is an

important differential diagnosis of painless

suboptimal vision following uneventful cataract

extraction. The pathogenesis is most likely

multifactorial, ultimately leading to the breakdown of

the blood-retinal barrier and cystic accumulation of

extracellular intraretinal fluid.

Visual loss occurs from retinal thickening and fluid

collection that distorts the architecture of the rod and

cone photoreceptors.6

The introduction of modern surgical techniques

including phacoemulsification and small incision

cataract surgery has contributed to a reduction in the

incidence of CME since it was initially reported by

Irvine in 1953.

The diagnosis of CME was previously made with

fluorescein angiography (which uses a dye that has

high probabilities of Anaphylactic Shock) after the

patient became symptomatic. However, the

emergence of OCT has provided a quick and

noninvasive means of diagnosis.7

OCT (Optical coherence tomography) offers a non-

invasive imaging technique that provides high

resolution cross sectional images of the macula. OCT

is similar to ultrasound imaging, only using light

rather than sound.The advantage of OCT is that we

can detect minute changes in the thickness of retina

especially in the macular area, which is concerned

with best visual acuity.8

OCT works on the principle of directing a beam of

near-infrared light from a broadband coherent light

source, (e.g., a superluminescent diode) at a target

tissue, and capturing light that is back-scattered from

that tissue.9

Patient factors predisposing to CME include

comorbidities with high vasoactive profile (diabetic

retinopathy, uveitis), while surgical factors include

inflammation-inducing complications such as

retained lens material, posterior capsular rupture,

vitreous loss and vitreous incarceration into the

incision site and anterior chamber and vitreomacular

traction. Advanced age has been also reported as a

risk factor for the development of the syndrome.9

However, many otherwise healthy patients who

undergo routine surgery continue to develop the

condition.

Aims and Objectives

To study the incidence of Macular Edema in cases

operated by the Conventional Extra Capsular Cataract

Excision(ECCE) and Small Incision Cataract Surgery

methods using Optical Coherence Tomography(OCT)

Materials and Methods

Study was a hospital based simple observational

study conducted over a span of 1year. 100 cases of

postoperative cataract, 50 operated by the

conventional ECCE, and 50 operated by the SICS

technique were evaluated during the study.

The proposal of the study was approved by the

Institutional Ethical Committee.

Cataract Surgery Patients operated by any other

(ICCE or Phacoemulsifiaction) method, Patients with

Diabetes Mellitus (because patients may have

preoperative diabetic maculopathy), Cases of

Traumatic Cataract, Cases of Developmental

Cataract, Cases of Complicated Cataract were

excluded from the study.Patients selected were those

fulfilling the inclusion and the exclusion criteria.

The patients included in the study were thoroughly

examined and evaluated regarding the postoperative

visual outcome. OCT of patients selected in the study

was done 4 weeks post operatively. Detailed Records

of the following were noted to see which patients fall

into the study criteria.

Preoperative systemic evaluation(which will include

–General health of the patient, proper control of

systemic diseases e.g. Diabetes and Hypertension,



51

CVS and Respiratory disease), Complete

haemogram, Blood Sugar Levels, HIV and HbSAg,

and any other specific investigations if it was advised

and needed was performed.

Detailed preoperative evaluation of the patient was

obtained from records which includedVisual Acuity,

Anterior Segment Examination with diffuse light and

Slit lamp Examination (to rule out any ocular disease

and septic focus), Intra Ocular Pressure, Sac

Syringing, Grading of cataract, Fundus Examination

with 90 D lens whenever possible, Macular Function

Tests for Visual prognosis and IOL power

calculation.

Post operative examination included Post operative

visual acuity with Pin hole improvement at discharge

and at the time of follow up at 4 weeks, Positive

Anterior segment findings and Posterior segment

examination with 90 D lens with special attention to

macular area at time of discharge and at the time of

follow up at 4 weeks.OCT was performed at the time

of 4 weeks follow up.

Patients did not have to bare any extra cost for the

OCT examination.

OCT was performedon the Zeiss Primus 200 machine

after the patient was explained the procedure and an

informed written consent was taken. Pupil was

dilated before the examination with1% tropicamide

and 5% phenylephrine eye drops. The patient was

seated comfortably at the Zeiss primus 200 Optical

Coherence Tomography machine in the Out Patient

Department (OPD) and his / her chin was placed on

the chin rest and forehead rested against the head rest.

The patient was asked to observe the light (fixation

point) with minimal blinking. The eye was scanned

using specific programs (Macular Thickness

Analysis). The Central subfield Macular Thickness

was measured and correlated clinically.

Data was entered in Microsoft Office Excel for

analysis.

Statistical analysis was done by using percentages,

mean and standard deviation.The two groups were

compared using paired and unpaired t tests, chi

square test and the Z test for difference between two

sample proportions.

Observations and Results

A total of 100 subjects, 50 operated by the

Conventional ECCE method and 50 by the SICS

method were included in the final statistical analysis.

The mean age of patients was 65±16.78 years and

Maximum number of patients were in the age group

of 61-70.

% of Males was 62% and % of Females was

38%.(Table 1).



52

Table 1: Age and Sex Distribution

Age Groups (Years) Males

No of Cases & in

%

Females

No of Cases & in

%

Total

No of Cases & in

%

<=50 3 2 5

51-60 14 8 22

61-70 32 19 51

71-80 12 7 19

81-90 1 2 3

>90 0 0 0

Total 62 38 100

56 patients (56%) underwent surgery in the right eye and 44 patients (44%) underwent surgery in the left eye.

(Graph1).

Graph 1: Laterality Distribution

56% 44%

Laterality Distribution

Right Eye

Left Eye

The mean Central Macular Thickness was 201.89 ± 96.79 microns.

The central macular thickness in patients operated by the Conventional ECCE method was 198.22 ± 57.60 microns

and in those operated by SICS method was 205.56 ± 124.56 microns(Graph 2).

International J. of Healthcare and

www.ijhbr.com

Graph 2: Mean Macular Thickness

13 of the 100 (13%) developed OCT pro

Macular Thickness of 396.33 ± 174.48 microns

Average Macular Thickness of 351.7 ± 92.24 microns

(SICS) with Average Macular Thickness of 451.3

Graph 3: OCT proven Macular Edema

Discussion

Pseudophakic Cystoid Macular Edema (PCME) or

Irvine-Gass syndrome – is an extracellular

accumulation of fluid in the fovea in the center of the

retina. PCME is the most common course of

unexpected postoperative visual reduction in patients

190195200205210

Macular Thickness on OCT at 1 month

0

20

40

60

No

of

Cas

es

OCT proven Macular Edema

International J. of Healthcare and Biomedical Research, Volume: 06, Issue: 01, October 2017,


13 of the 100 (13%) developed OCT proven Post Cataract Macular Edema (PCME) at 1 month with Average

± 174.48 microns of which8 (16%) patients underwent Conventional ECCE with

± 92.24 microns.5 (10%) patients underwent Small Incision Cataract Surgery

(SICS) with Average Macular Thickness of 451.3 ± 237.89 microns(Graph 3)

Pseudophakic Cystoid Macular Edema (PCME) or

is an extracellular

accumulation of fluid in the fovea in the center of the

retina. PCME is the most common course of

unexpected postoperative visual reduction in patients

who experienced an otherwise uncomplicated cataract

operation with initially excellent visual results.

advent of phacoemulsification and small incision

cataract surgery has reduced the incidence of PCME,

but the sheer volume of cataract surgery still makes

PCME a prevalent morbidity.

198.22 205.56

Macular Thickness on OCT at 1 month

Average

Macular

Thickness

(Microns)

8 5

42 45

OCT proven Macular Edema

at 1 month

Abse

nt

01, October 2017, 49-57

53

(PCME) at 1 month with Average

of which8 (16%) patients underwent Conventional ECCE with

.5 (10%) patients underwent Small Incision Cataract Surgery

an otherwise uncomplicated cataract

operation with initially excellent visual results.10 The

advent of phacoemulsification and small incision

cataract surgery has reduced the incidence of PCME,

but the sheer volume of cataract surgery still makes

Average

Macular

Thickness

(Microns)



54

PCME pathogenesis is likely multifactorial, but

inflammation caused by surgical manipulation

appears to be the major cause. Inflammatory

mediators break down the blood–aqueous and blood–

retinal barriers, leading to increased vascular

permeability.11 Transudate accumulates in the outer

plexiform and inner nuclear layers of the retina and

microcysts coalesce into cysts.10

Surgical complications that predispose eyes to PCME

include vitreous loss, vitreous traction at incision

sites, vitrectomy for retained lens fragments, iris

trauma, posterior capsule rupture, intraocular lens

(IOL) dislocation, early postoperative capsulotomy,

and the use of iris-fixated or anterior chamber IOLs

.42

Eyes with diabetic maculopathy, uveitis, retinal

vein occlusions (RVO), epiretinal membranes, and

prostaglandin analogs were also risk factors for

PCME.

The symptoms of PCME are various degrees of

visual acuity reduction and in some cases distorted

vision or metamorphosis.

The incidence of clinical PCME peaks at

approximately 4–6 weeks postoperatively. Most

patients with clinical PCME will present with blurry

vision, and biomicroscopy will show retinal

thickening and loss of the foveal depression. Findings

are best observed using a fundus contact lens, and

red-free light may allow better visualization of cystic

changes. Fluorescein angiography findings include

retinal telangiectasis, capillary dilatation, and leakage

from perifoveal capillaries in the early frames

developing into the classic ‘petalloid’ pattern in late

frames. OCT has become widely adopted and allows

convenient monitoring of disease activity. PCME is

characterized by loss of the foveal depression, retinal

thickening, and cystic hyporeflective lesions.

Clinically significant PCME is supposed to occur in

less than 2% of the patients13

. However, 11-40% are

reported to have some degree of, often subclinical,

PCME in the early postoperative period. The

difference in reported incidence in different studies is

probably due to an ambiguous definition of the early

stages of PCME and variation in patient

characteristics 14-22

.

In our study 50 patients operated by the Conventional

ECCE method and 50 by the SICS method were

studied.

The mean age of the subjects in the study was was

65±16.78 years. Maximum number of patients (51%)

were in the age group of 61-70.

2% of subjects were male and 38% female. This was

similar to most studies conducted in rural India. The

reason for the same being the illiteracy, the gender

bias and the ignorance about the health issues which

prevails among the rural population, more so among

women.

56% underwent Cataract surgery in the right eye and

44% underwent Cataract surgery in the left eye.

The Mean Central Subfield Macular thickness was

201.89 ± 96.79 microns. The central macular

thickness in patients operated by the Conventional

ECCE method was 198.22 ± 57.60 microns and in

those operated by SICS method was 205.56 ± 124.56

microns. Our findings are consistent with Neumaieret

al23

who found the macular thickness four weeks after

surgery to be 173 µm ± 14.Our results also correlated

with Wang et al24 who found the Macular thickness 1

month after surgery to be 207.98 ± 26.99.

13 of the 100 (13%) developed OCT proven

Pseudophakic Cystoid Macular Edema (PCME) at 1

month. Our findings were consistent with Baker et

al25 who found the incidence of PCME in non

diabetic patients to be 10%.Manjuet al26

found the

incidence of PCME to be 9.87% 1 month following

Cataract surgery.

Average Macular Thickness of 396.33 ± 174.48

microns of which8 (16%) patients underwent

Conventional ECCE with Average Macular

Thickness of 351.7 ± 92.24 microns. 5 (10%) patients

underwent Small Incision Cataract Surgery (SICS)



55

with Average Macular Thickness of 451.3 ± 237.89

microns. These results show that SICS is a superior

technique than Conventional ECCE as far as PCME

is concerned. This may be due to the shorter duration

of surgery and lesser handling of Intraocular tissue in

SICS, leading to lesser release of pro inflammatory

factors, that are thought to be associated with

causation of PCME.

We used OCT as a diagnostic tool in our study to

Compute the central macular thickness and to detect

the presence of Macular edema. Besides being non

invasive and easy to operate, we found it to be very

useful in uneducated rural population who would not

be very cooperative for a detailed Fundus

Examination on Slit Lamp Biomicroscopy with 90D

lenses or an invasive procedure like FFA. Brown et

al27

reported that OCT is in good agreement with

contact lens biomicroscopy for detecting the presence

or absence of Macular Edema and possibly superior

in mild cases. In addition, a comparison by Antcliffet

al28

demonstrated that OCT is as effective as

fluorescein angiography in detecting Macular Edema

in uveitic patients.

OCT provides objective, quantifiable, and continuous

measurements of macular thickness in contrast to the

subjective and categorical interpretation of leakage

shown by fluorescein angiography or clinical

examination. Furthermore, several researchers have

reported that increased retinal thickness correlates

more strongly with visual acuity than the presence of

leakage shown by fluorescein angiography.29-32

Topographical studies have shown that subclinical

ME caused by different diseases may only be

detected by OCT. The advantages of OCT over other

imaging modalities available include its non-invasive

approach, quick imaging acquisition and safety

profile.33

Besides identifying CMO, OCT enables quantitative

evaluation of macular thickness over time, a feature

not possible with FA. The visualization of patients

serial data using the heat map allows the possibility

of correlating patterns of change in macular thickness

with other clinical symptoms of interest in the future.

Such analyses are missed and not possible with

routine statistical tests.34

We had few limitations in our study. Since our study

was conducted in rural area of Maharashtra some

patients were lost to follow up and hence had to be

excluded from the study. The outlook of rural

patients towards their health was skewed. Some

patients did not comply with the postoperative

treatment regimen which may have led to sustained

inflammation post operatively

Conclusion

Incidence of Pseudophakic Cystoid Macular Edema

at 1 month postop was 13%.

SICS was found to be a superior technique than

Conventional ECCE for Cataract surgery in terms of

development of PCME (10% in SICS as compared to

16% in Conventional ECCE)

OCT is an excellent non-invasive tool for macular

thickness measurement, which can be used in routine

practice for greater diagnostic accuracy in PCME.

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