Fig. 9.4.34 OCT images of MICS incisions showing an example of endothelial bulge (a) and endothelial bullae (b) (white arrows)

a

b

evaluation of the incision, these group of eyes with BMICS have been compared with an equal number of eyes (25) having the same grade of cataract deepening on the Lens Opacities Classification System III [23]. The second group of patients underwent surgery using the other method currently available for microincision lens surgery using a protected (sleeved) tip, which is the microcoaxial phacoemulsification with an incision of 2.2 mm (microphaco) [24–26].

9.4.6 Results

9.4.6.1Visual, Refractive and Biomicroscopic Outcomes

Only UCVA (uncorrected visual acuity) at 1 week and 1 month postoperatively were statistically significant. However, BSCVA (best spectacle corrected visual

acuity), postoperative sphere and cylinder showed no statistical difference (Fig. 9.4.35, Table 9.4.1).

MICS showed less corneal edema at the first postoperative day by slit-lamp biomicroscopy (Table 9.4.1).

9.4.6.2 Incision Imaging (OCT) Outcomes

Three different OCT incision parameters were evaluated: pachymetric (corneal thickness) values, qualitative (non numerical) incision data and quantitative (numerical) incision data. When comparing both groups, we observed the following results:

Pachemetry measurements (Fig. 9.4.36): BMICS showed less corneal thickness in an area of 5–7 mm of the cornea but only on day-1 (659.92 ± 56.74 vs. 697.00 ± 80.56 μm; p = 0.066).

Qualitative (descriptive) incision data are summarized in (Table 9.4.2) from which we had the following observations: No misalignment of epithelial edge were

Table 9.4.1 Comparison

of visual acuities, refraction, slit-lamp examination and IOP between both study groups, day 1, week 1 and month 1 postoperatively.

BSCDVA (mean ± SD)

Fig. 9.4.36 OCT measured central corneal thickness and mean thickness in an area of 2–5 and 5–7 mm of the cornea among study groups, day 1, week 1 and month 1 postoperatively (P value denotes the only significant difference)

CCT

present, and at 1 month, there was no misalignment of either the epithelial or endothelial edges, or Descemet’s detachments (Fig. 9.4.37).

Quantitative incision data (incision angle and thickness) revealed that corneal thickness at 1 mm temporal to the incision was slightly less in microphaco only on day-1 (0.95 ± 0.14 vs. 0.88 ± 0.13 mm; p = 0.09), (Fig. 9.4.38). Angle of the incision trigonometrically calculated revealed excellent incision quality in both groups with no statistically significant differences (Table 9.4.3, Figs. 9.4.39 and 9.4.40).

9.4.6.3Topographic and Aberrometric

Outcomes

At 1 month postsurgery, corneal topography maps revealed that the postoperative corneal powers didn’t differ (44.12 ± 2.26 D vs. 43.96 ± 1.76 D; p = 0.90). Corneal asphericity differs significantly between BMICS and microphaco, with a more prolate topography in the BMICS group (Q 4.5 mm, −0.08 ± 0.39 vs. 0.2 ± 0.72; p = 0.05; Q 8 mm, −0.22 ± 0.45 vs. 0.05 ± 0.49; p = 0.04), (Fig. 9.4.41).

Fig. 9.4.37 OCT images showing evolution of the incision of a MICS case throughout the follow-up visits

Day 1

Week 1

Month 1

Fig. 9.4.38 OCT measured corneal thickness in the area of the incision and at 1 mm at each side of the incision throughout the follow-up visits

Table 9.4.3 OCT measured incision thickness, central and at 1 mm on either side of the incision and incision angle among study groups, day 1, week 1, and month 1 postoperatively

Fig. 9.4.39 OCT images showing angle of the incision MICS vs. microphaco (white arrows)

MICS

Microphaco

MICS Microphaco

Fig. 9.4.40 Evolution of the angle of the incision MICS vs. microphaco throughout the follow-up visits

Corneal aberrations with the corresponding p values are shown (Fig. 9.4.42) denoting that RMS values for astigmatism and HOA were slightly better in BMICS, p = 0.06 and 0.05 respectively. Strehl ratio didn’t differ significantly between groups (0.12 ± 0.03 vs. 0.12 ± 0.05; p = 0.53).

No statistically significant differences between groups were observed in ocular aberrometry parameters: RMS total (1.97 ± 0.91 vs. 2.35 ± 1.12 μm; p = 0.2) and RMS higher-order aberrations (HOA) (0.64 ± 0.22 vs. 0.74 ± 0.1 μm; p = 0.1) with good optical quality in both groups (Fig. 9.4.43).

0.70

MICS Microphaco

MICS Microphaco

Fig. 9.4.42 Corneal aberrations at 6-mm pupil diameter for both groups with the corresponding p values

9.4.7Special Focus on the Role of OCT

in the Evaluation of Incision Quality in BMICS

We have to refer that our clinical observations about BMICS incision were subsequently confirmed objectively by OCT assessment parameters (Fig. 9.4.44), confirming the role of OCT as an accurate quantitative tool assessing the incision effect and quality [17].

The importance of OCT as a tool for evaluating tiny incisions results in the fact that it is a noncontact modality and therefore, introduces no artifacts and is more precise than slit-lamp evaluations, (Fig. 9.4.45) [17, 27, 28].

An important parameter of incision quality is the angle of the incision. Our study [21] shows that BMICS provides an incision angle previously described as

critical for self-sealability [29], to obtain secure ocular incisions unaffected by the level of IOP, especially among sutureless cataract incisions, which provide a perfectly coapted barrier against the invasion of pathogenic organisms, supported by the fact that we did not have any single case of endophthalmitis in our study [21]. Although variable and sometimes poor incision apposition with fluctuation with IOP has been reported by many authors [27, 29–31], our results were obtained using a large number of eyes, with longer follow-up, compared with others who used either postmortem human globes or animal eyes.

Interestingly, we may encounter a localized subclinical Descemet’s membrane detachment. This could be explained by double-cut incisions or by stretching the incisions during IOL insertion [17, 21, 32].