Dr. Birendra Prasad Kashyap,
K02624, Dr. Bharti Kashyap
INTRODUCTION
Many studies have demonstrated that Diabetic Retinopathy progresses in approximately 10–30% of patients after cataract surgery, although some authors have hypothesized that the progression of DR after cataract surgery is due simply to the natural course of the condition, and that the progression is independent of the surgery.
Recently, Femtosecond Lasers have demonstrated higher precision and safety of capsulorhexsis and reduced the phacoemulsification power as compared to traditional procedures. But experimental and clinical studies has demonstrated that application of the suction causes short but considerable fluctuations (upto 16 mmHg in LenSx technique) in intraocular pressure which can induce several changes in ocular structures.
On the other hand, phacoemulsification itself may induce post-operative macular oedema (prevalence of 0.1 % to 12 %) owing to its traumatic effect. Although the pathophysiology of CME is primarily due to intraocular inflammation secondary to surgical manipulation, increase in vascular permeability and fluid leakage through Retinal Pigment Epithelium due release of prostaglandins (higher in diabetes) has also attributed to the cause of CME formation.
With new modifications in Femtosecond platform lower energy is now used for capsulotomy and incision. With the induction of softfit contact lens and Patient Interface the complications which were present earlier with harder surface (i.e. deformity of cornea, increased corneal folds, need for higher laser energy and also leading to increased IOP) has reduced.
The purpose of the study was to investigate impact of Femtosecond Laser Assisted Cataract surgery with traditional phacoemulsification cataract surgery on early post-operative macular thickness in diabetic patients.
PATIENTS AND METHODS
This is a prospective, non-randomized and comparative case series of patients by a single surgeon, who underwent Femtosecond Laser assisted cataract surgery on LenSx platform and traditional Phacoemulsification cataract surgery performed during the period of October 2014 to September 2015.
Exclusion criteria
- Cataract due to causes other than age or diabetes,
- History of ocular inflammation or surgery,
- H/o of uveitis, Glaucoma and other retinal complications like RVO, ERM etc
- Any pathology of the macula or optic nerve due to causes other than diabetes
- Leathery White cataract, Hypermatured and Dense PSCC & PPC were excluded in this study
- Patient refusal to participate.
- Any Per-operative complication
35 patients underwent uneventful Phacoemulsification Cataract Surgery with IOL implantation (Centurion Vision System, Alcon) and 35 patients underwent Femtosecond Laser Assisted Cataract Surgery (LenSx, Alcon & Centurion Vision System, Alcon) followed by IOL Implantation.
At the time of cataract surgery, all patients underwent implantation of a hydrophobic acrylic IOL (Alcon Laboratories). All surgeries were performed by a single surgeon who has experience of 18 years.
All patients had a baseline pre operative assessment including anterior and posterior segment examination. The central retinal (foveal) thickness of all patients was measured by Optovue optical coherence tomography pre-operatively 2 hours before surgery, and at 7 days, and 45 days after surgery. Measurements were provided for three concentric regions. The central disc foveal region was a region with a radius of 1.0 mm (CSMT), and the inner and outer rings had radii of 3.0 mm and 6.0 mm an were divided into four quadrants. The average retinal thickness was provided for each of the nine regions and these results were calculated.
Uncorrected Visual Acuity and Best-corrected visual acuity were determined at each examination. Best-corrected visual acuity on decimal charts was converted to the logarithm of minimal angle of resolution (logMAR) scale for statistical analysis.
In Femtosecond Group, patients underwent LenSx Pre treatment procedure by fragmentation mode of laser treatment followed by Phacoemulsification by Centurion Vision System and IOL implantation by Autosert injector.
All surgeries included in the analysis were uneventful and the IOLs were implanted accurately within the capsular bag.
Post operatively, diagnosis of clinical macular oedema was made in patients who presented with unexpected poor visual acuity or deteriorating visual acuity at subsequent visits. Funduscopy and Optical Coherence Tomography were done to confirm the evidence of Macular Oedema.
STASTISTICAL ANALYSIS
Results between Femtosecond Laser assisted Cataract surgery and phacoemulsification group in the Diabetic patients were compared using a one way analysis of variance. The results are expressed as Mean ± SD. A p value < 0.05 was considered statistically significant. All statistical calculation was performed using IBM SS statistics Data Editor.
RESULTS:-
70 eyes of 70 patients were included in this study, of which 35 eyes had Femtosecond laser assisted cataract surgery followed by IOL implantation and 35 eyes underwent phacoemulsification cataract surgery.
Demographic representation of study groups is shown in the table below
| Baseline demographics of the study patients | |||
| PARAMETERS | LASER GROUP | PHACO GROUP | P VALUE |
| SEX | M= 16, F= 19 | M=18, F=17 | 0.406 (ns) |
| AGE | 61.84 ± 4.34 | 60.72 ± 5.09 | 0.313 (ns) |
| LATERALITY | R=18, L=17 | R= 16, L= 19 | 0.406 (ns) |
| BCVA | 0.9583 ± 0.096 | 0.9391 ± 0.137 | 0.502 (ns) |
The average age of the patients (±standard deviation [SD]) in the Femtosecond laser group was 61.84 ± 4.34 years, with a range of 50–70 years; there were 16 men and 19 women. In the Phacoemulsification group, the average age was 60.72 ± 5.09 years, (range 50- 69 years); with 18 male and 17 female.
Out of the 70 eyes operated, 34 were operated for Left Eye & 36 was done on Right Eye.
In the laser group, median of Best corrected visual acuity (BCVA) was 0.021 ± 0.053 log MAR and 0.034 ± 0.051 log MAR for the phacoemulsification group at 45 days post operatively.
There were no significant differences in average of foveal thickness preoperatively between the Laser and Phacoemulsification group measured at 7 days and 45 days by Optical Coherence Tomography.
Table 2 shows the Average Retinal Thickness Values.
| Average Retinal thickness values Preoperatively, 7 days and 45 days after Femtosecond Laser and Conventional Phacoemulsifcation measured by Optical Coherence Tomography | ||||
| TIME | PARAMETERS | LASER GROUP | PHACO GROUP | P VALUE |
| PRE-OPERATIVE | FOVEA | 207 (179 to 241) | 208 (172 to 239) | 0.767 |
| PARAFOVEA | 270 (205 to 297) | 272 (207 to 301) | 0.799 | |
| PERIFOVEA | 262 (238 to 291) | 262 (221 to 295) | 0.781 | |
| 1 WEEK | FOVEA | 217 (188 to 252) | 217 (179 to 261) | 0.949 |
| PARAFOVEA | 284 (234 to 331) | 288 (219 to 401) | 0.675 | |
| PERIFOVEA | 272 (230 to 301) | 279 (249 to 367) | 0.188 | |
| 45 DAYS | FOVEA | 215 (182 to 252) | 213 (174 to 244) | 0.468 |
| PARAFOVEA | 281 (215 to 312) | 286 (218 to 389) | 0.667 | |
| PERIFOVEA | 273 (246 to 300) | 277 (246 to 376) | 0.329 | |
The post operative retinal thickness at 7 days in Femtosecond group ranged from 188 to 252 in fovea, 234 to 331 in the parafoveal quadrant and 230 to 301 in the perifoveal quadrant. Whereas the values of 7th day Post Operative CRT ranged from 179 to 261, 219 to 201 and 249 to 367 respectively in the Phacoemulsification group.
The table below shows the difference of macular thickness at different areas between the two groups.
| DIFFERENCE OF MACULAR THICKNESS MEASURED A DIFFERENT AREAS IN EYES THAT UNDER WENT FEMTOSECOND LASER ASSISTED AND CONVENTIONAL PHACOEMULSIFICATION | ||||
| TIME | MACULAR AREA | DIFFERENCE (µm) | 95 % CONFIDENCE LEVEL (µm) | P VALUE |
| 7 DAYS | FOVEA | 1.372 | ( -1.3022 TO 4.036) | 0.309 |
| PARA FOVEA | -1.257 | (-10.936 TO 8.468) | 0.796 | |
| PERI FOVEA | -0.8857 | (-12.161 TO 10.389) | 0.876 | |
7 day post operative Macular thickness in the Femtosecond Laser was found to be similar in all the nine zones when compared to the Phacoemulsification group. The difference of change of foveal thickness preoperatively and at 7 days was found to be 1.372 µm (p=0.309), parafoveal area was -1.257 µm (p=0.796) and perifoveal quadrant was -0.8857 µm (p=0.876) respectively.
The post operative retinal thickness at 45 days in Femtosecond group ranged from 182 to 252 in fovea, 215 to 3121 in the parafoveal quadrant and 246 to 300 in the perifoveal quadrant. Whereas the values of 7th day Post Operative CRT ranged from 174 to 244, 218 to 389 and 246 to 367 respectively in the Phacoemulsification group.
The table below shows the difference of macular thickness at different areas between the two groups.
| DIFFERENCE OF MACULAR THICKNESS MEASURED A DIFFERENT AREAS IN EYES THAT UNDER WENT FEMTOSECOND LASER ASSISTED AND CONVENTIONAL PHACOEMULSIFICATION | ||||
| TIME | MACULAR AREA | DIFFERENCE (µm) | 95 % CONFIDENCE LEVEL (µm) | P VALUE |
| 45 DAYS | FOVEA | 1.943 | ( 0.252 TO 5.634) | 0.135 |
| PARA FOVEA | -3.629 | (-12.459 TO 5.202) | 0.415 | |
| PERI FOVEA | -5.343 | (-13.067 TO 2.381) | 0.172 | |
Similarly 45 day post operative Macular thickness in the Femtosecond Laser was found to be similar in all the nine zones when compared to the Phacoemulsification group.
The difference of change of foveal thickness preoperatively and at 7 days was found to be 1.943 µm (p=0.135), parafoveal area was -3.629 µm (p=0.415) and perifoveal quadrant was -5.343 µm (p=0.172) respectively.
Discussion & conclusion:-
The incidence of clinical Cystoid macular oedema with femtosecond laser assisted cataract surgery in long term follow up studies has yet to be reported although one case series has recently been published, suggesting no difference attributable to femtoseoned laser assisted cataract surgery.
Our prospective, non randomized and comparative case study tried to further evaluate this study on diabetic populations.
Cysoid macular oedema is now typically less because of prophylactic pre and post operative topical NSAID use combined with post operative topical steroids. Using a larger sample size, further study is warranted to examine the changes in macular oedema that occur in eyes with active maculopathy.
Modern cataract surgery techniques and low ultrasound technology have reduced the incidence of CME as a postoperative complication. Femtosecond laser assisted cataract surgery minimizes inflammation, trauma and ultrasound use resulting in reduction in the incidence of CME in Diabetic population.
From these results, we conclude that both methods of cataract extraction are equally safe in terms of early macular thickness in diabetic population.
Limitation of our study include a relatively smaller sample size and short follow up period with no active diabetic macular thickness.
CONCLUSION:-
With Topical Pre and post NSAID drop coverage FLACS and MICS groups have shown no significant difference on Post operative macular status in diabetic population with pre operative normal retina.
Lower Energy and lesser soft fit suction parameters of upgraded LenSx Platform have reduced the incidence of post-operative CME. Laser Speed has increased from 30 Khz to 50 KHz in the upgraded version of software Femtosecond laser assisted cataract surgery minimizes inflammation, trauma and ultrasound use resulting in reduction in the incidence of CME in Diabetic population.
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