Penetrating Keratoplasty vs DALK: Comparison of Outcomes
Penetrating Keratoplasty vs DALK: Comparison of Outcomes
A total of 174 eyes of 140 consecutive patients was included. One hundred and four eyes underwent DALK surgery. Conversion to PK was needed in five eyes because of the macroperforation. Therefore, the PK group consisted of 75 eyes of 55 patients and the DALK group consisted of 99 eyes of 80 patients. Complete DM exposure could be achieved in 88 (88.9%) cases via the big-bubble in the dDALK group and a layer-by-layer manual stromal dissection was needed in 11 eyes (11.1%) in the pdDALK group.
Table 1 summarises the preoperative data of the eyes. No statistically significant differences between groups were found with regard to age, UCVA, BSCVA, corneal astigmatism and maximal keratometric readings (p>0.05 for all).
No intraoperative complication occurred in the PK group. Microperforation occurred in eight eyes (8.0%) in the DALK group. Interface haze was not seen in any eyes. Double anterior chamber was seen in one eye (1.0%) and resolved after intracamaral air injection. Graft rejection episodes were seen in seven eyes (9.3%) in the PK group; but no grafts were lost as a result of graft rejection. Stromal graft rejection episodes were seen in one eye (1.0%) in the DALK group, which was completely resolved with topical corticosteroids.
The mean period of time between surgery and complete suture removal was of 16.60±5.80 months (range 12–28 months) and 12.78±3.02 months (range 8–20 months) in the PK and DALK groups, respectively (p=0.04). So suture removal and the visual examination giving the definitive outcomes could be performed earlier in the DALK group. The mean period of time between surgery and the last complete postoperative examination was 25.53±6.18 months (range 18–36 months) and 21.54±4.25 months (range 15–26 months) in the PK and DALK groups, respectively (p=0.09).
Postoperative BSCVA was 20/40 or better in 64 eyes (85%) in the PK group and in 82 eyes (83%) in the DALK group (p>0.05). Table 2 summarises the postoperative visual outcome and refractive status of the study eyes. No significant differences between the DALK and PK groups in any postoperative visual and refractive parameter were found (p>0.05). Comparing the subgroups, postoperative visual and refractive parameters were not significantly different between the dDALK and pdDALK groups (p>0.05).
Figure 1 shows the mean CSF under photopic and mesopic conditions for the two groups of eyes. No significant differences in photopic contrast sensitivity were found for each of the spatial frequencies between the DALK and PK groups (p values 0.28 for three cycles/degree, 0.43 for six cycles/degree, 0.46 for 12 cycles/degree and 0.48 for 18 cycles/degree). However, mesopic contrast sensitivity for three cycles/degree was significantly higher in the DALK group (p=0.01). For the remaining spatial frequencies in mesopic condition, no significant differences were detected (p values; 0.09 for six cycles/degree, 0.37 for 12 cycles/degree and 0.48 for 18 cycles/degree). Comparing the subgroups, the mean CSF under photopic and mesopic conditions were not different between the dDALK and pdDALK groups for each of the spatial frequencies (p>0.05).
(Enlarge Image)
Figure 1.
Mean contrast sensitivity function under photopic and mesopic conditions for two groups analysed in the study: PK, penetrating keratoplasty group (black line), and DALK, deep anterior lamellar keratoplasty (grey line).
Wavefront aberrometric analyses were obtained in 28 eyes in the PK group (37%) and 50 eyes (50%) in the DALK group. Figure 2 shows mean and standard deviations of the ocular aberrometric parameters obtained with the Zywave system. Parameters analysed included total root mean square (RMS), higher order RMS (HOA RMS), and RMS of HOA without considering the Zernike term corresponding to the primary spherical aberration (HOA RMS without Z(4,0)). No significant differences between groups were detected (p values were 0.88 for total RMS, 0.80 for HOA RMS; 0.39 for HOA RMS without Z(4,0). We could not make a comparison between the dDALK and pdDALK groups because no pdDALK patient had wavefront aberrometric analysis.
(Enlarge Image)
Figure 2.
Mean values and standard deviations of the ocular aberrometric parameters measured with the Zywave system in the two groups analysed in the study. PK, penetrating keratoplasty (grey bars); DALK, deep anterior lamellar keratoplasty (white bars); total RMS, total root mean square; HOA RMS, higher order aberration RMS; HOA w/o Z(4,0) RMS, RMS of HOA without considering the Zernike term corresponding to the primary spherical aberration.
Figure 2 Mean values and standard deviations of the ocular aberrometric parameters measured with the Zywave system in the two groups analysed in the study. PK, penetrating keratoplasty (grey bars); DALK, deep anterior lamellar keratoplasty (white bars); total RMS, total root mean square; HOA RMS, higher order aberration RMS; HOA w/o Z(4,0) RMS, RMS of HOA without considering the Zernike term corresponding to the primary spherical aberration.
Results
Operative and Postoperative Data
A total of 174 eyes of 140 consecutive patients was included. One hundred and four eyes underwent DALK surgery. Conversion to PK was needed in five eyes because of the macroperforation. Therefore, the PK group consisted of 75 eyes of 55 patients and the DALK group consisted of 99 eyes of 80 patients. Complete DM exposure could be achieved in 88 (88.9%) cases via the big-bubble in the dDALK group and a layer-by-layer manual stromal dissection was needed in 11 eyes (11.1%) in the pdDALK group.
Table 1 summarises the preoperative data of the eyes. No statistically significant differences between groups were found with regard to age, UCVA, BSCVA, corneal astigmatism and maximal keratometric readings (p>0.05 for all).
No intraoperative complication occurred in the PK group. Microperforation occurred in eight eyes (8.0%) in the DALK group. Interface haze was not seen in any eyes. Double anterior chamber was seen in one eye (1.0%) and resolved after intracamaral air injection. Graft rejection episodes were seen in seven eyes (9.3%) in the PK group; but no grafts were lost as a result of graft rejection. Stromal graft rejection episodes were seen in one eye (1.0%) in the DALK group, which was completely resolved with topical corticosteroids.
Refractive and Visual Outcome
The mean period of time between surgery and complete suture removal was of 16.60±5.80 months (range 12–28 months) and 12.78±3.02 months (range 8–20 months) in the PK and DALK groups, respectively (p=0.04). So suture removal and the visual examination giving the definitive outcomes could be performed earlier in the DALK group. The mean period of time between surgery and the last complete postoperative examination was 25.53±6.18 months (range 18–36 months) and 21.54±4.25 months (range 15–26 months) in the PK and DALK groups, respectively (p=0.09).
Postoperative BSCVA was 20/40 or better in 64 eyes (85%) in the PK group and in 82 eyes (83%) in the DALK group (p>0.05). Table 2 summarises the postoperative visual outcome and refractive status of the study eyes. No significant differences between the DALK and PK groups in any postoperative visual and refractive parameter were found (p>0.05). Comparing the subgroups, postoperative visual and refractive parameters were not significantly different between the dDALK and pdDALK groups (p>0.05).
Contrast Sensitivity Outcome
Figure 1 shows the mean CSF under photopic and mesopic conditions for the two groups of eyes. No significant differences in photopic contrast sensitivity were found for each of the spatial frequencies between the DALK and PK groups (p values 0.28 for three cycles/degree, 0.43 for six cycles/degree, 0.46 for 12 cycles/degree and 0.48 for 18 cycles/degree). However, mesopic contrast sensitivity for three cycles/degree was significantly higher in the DALK group (p=0.01). For the remaining spatial frequencies in mesopic condition, no significant differences were detected (p values; 0.09 for six cycles/degree, 0.37 for 12 cycles/degree and 0.48 for 18 cycles/degree). Comparing the subgroups, the mean CSF under photopic and mesopic conditions were not different between the dDALK and pdDALK groups for each of the spatial frequencies (p>0.05).
(Enlarge Image)
Figure 1.
Mean contrast sensitivity function under photopic and mesopic conditions for two groups analysed in the study: PK, penetrating keratoplasty group (black line), and DALK, deep anterior lamellar keratoplasty (grey line).
Wavefront Aberration Outcome
Wavefront aberrometric analyses were obtained in 28 eyes in the PK group (37%) and 50 eyes (50%) in the DALK group. Figure 2 shows mean and standard deviations of the ocular aberrometric parameters obtained with the Zywave system. Parameters analysed included total root mean square (RMS), higher order RMS (HOA RMS), and RMS of HOA without considering the Zernike term corresponding to the primary spherical aberration (HOA RMS without Z(4,0)). No significant differences between groups were detected (p values were 0.88 for total RMS, 0.80 for HOA RMS; 0.39 for HOA RMS without Z(4,0). We could not make a comparison between the dDALK and pdDALK groups because no pdDALK patient had wavefront aberrometric analysis.
(Enlarge Image)
Figure 2.
Mean values and standard deviations of the ocular aberrometric parameters measured with the Zywave system in the two groups analysed in the study. PK, penetrating keratoplasty (grey bars); DALK, deep anterior lamellar keratoplasty (white bars); total RMS, total root mean square; HOA RMS, higher order aberration RMS; HOA w/o Z(4,0) RMS, RMS of HOA without considering the Zernike term corresponding to the primary spherical aberration.
Figure 2 Mean values and standard deviations of the ocular aberrometric parameters measured with the Zywave system in the two groups analysed in the study. PK, penetrating keratoplasty (grey bars); DALK, deep anterior lamellar keratoplasty (white bars); total RMS, total root mean square; HOA RMS, higher order aberration RMS; HOA w/o Z(4,0) RMS, RMS of HOA without considering the Zernike term corresponding to the primary spherical aberration.
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