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A novel blunt dissection technique to treat modified deep anterior lamellar keratoplasty (DALK)-associated high astigmatism.

ABSTRACT:

Objectives

To describe a new surgical technique to correct a high astigmatism following modified deep anterior lamellar keratoplasty (DALK) and to evaluate the associated clinical outcomes.

Methods

Retrospective interventional case series included eyes with high astigmatism following modified DALK performed between July 2012 and June 2016. The prevalence of keratometric astigmatism (KA) higher than 4.5 diopters (D) was evaluated after complete suture removal. Surgical correction was obtained by opening the surgical wound at the steeper meridian and carrying out a blunt dissection at the graft-host surface of contact under keratoscopic control. KA, Refractive astigmatism (RA), and best spectacle-corrected visual acuity (BSCVA) were measured preoperatively and at 1, 12, and 24 months postoperatively. Vector analysis of 1 year change in KA was performed.

Results

High astigmatism was found in 47 of 511 eyes (9.2%). KA (mean ± standard deviation [SD]) decreased from 7.67 ± 2.78 to 3.10 ± 1.37 D at 1 month after astigmatic correction (p < 0.001) with no subsequent significant change. Vector analysis of 1 year change in KA: surgically induced astigmatism was 5.30 ± 3.29 D and mean absolute angle of error was 6.97 ± 4.25°. BSCVA improved from 0.21 ± 0.20 logMAR preoperatively to 0.11 ± 0.13 logMAR (p < 0.001); RA decreased from 6.32 ± 2.56 to 2.61 ± 1.05 D (p < 0.001). No intra- or post-operative complications occurred.

Conclusions

High astigmatism is present in <10% of cases after modified DALK and can be effectively managed by means of blunt relaxing dissection at the graft-host junction.

SUBMITTER: Elkadim M

PROVIDER: S-EPMC7376167 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroudPrevious studies of internal graft-host malappositions have not dealt with the precise ways in which each malapposition affected post-penetrating keratoplasty (post-PK) visual outcomes. In this study, we reviewed our post-PK and post-deep anterior lamellar keratoplasty (post-DALK) keratoconic patients and used anterior segment optical coherence tomography (AS-OCT) to evaluate the associations between graft-host interface (GHI) characteristics and visual outcomes.MethodsNovel GHI metrics included: mean graft-host touch (GHT), total prevalence of malapposition proportion (Pm), frequency of apposition (F), size of malapposition (Sm), junctional graft thickness (Tg), junctional host thickness (Th) and the absolute value of difference between Tg and Th (|Tg-Th|). We connected the external and internal junction points of GHI (GHT) and drew a straight line through the central point, perpendicular to both sides of the cornea. Tg and Th were the thicknesses at cross-points 1?mm away from the meeting point on the external side of the graft and host, respectively. Linear regression analysis was used to describe associations between GHI metrics and postsurgical visual outcomes [logarithm of minimum angle of resolution best-corrected visual acuity (logMAR BCVA), spherical equivalent diopter (SE), diopter of spherical power (DS), diopter of cylindrical power (DC) and keratometric astigmatism (Astig value)].ResultsWe enrolled 22 post-PK and 23 post-DALK keratoconic patients. Compared with the regular-apposition results, GHT was decreased in step and gape patterns, and increased in hill and tag patterns. SE increased averagely by 6.851, 5.428 and 5.164 diopter per 1% increase in: F (step) [??=?6.851; 95% Confidence interval (CI)?=?2.975-10.727; P?=?0.001]; F (graft step) [??=?5.428; 95% CI?=?1.685-9.171; P?=?0.005]; and Pm [??=?5.164; 95%CI?=?0.913-9.146; P?=?0.018], respectively. SE increased averagely by 0.31 diopter per 10-?m increment in |Tg-Th| [??=?0.031; 95% CI?=?0.009-0.054; P?=?0.007]. LogMAR BCVA increased (on average) by 0.01 per 10-?m increment in both GHT [??=?0.001; 95% CI?=?0-0.002; P?=?0.030]. and Tg [??=?0.001; 95% CI?=?0.001-0.002; P?=?0.001]. Astig value increased on average by 0.17 diopter per 10-?m increment in Sm [??=?0.017; 95% CI?=?0-0.033; P?=?0.047].ConclusionThis investigation of GHI characteristics suggests explanations for varied ametropia in keratoconic eyes and has potential significance as a reference for promoting pre-surgical planning and technology for corneal transplantation.