4.8Case 8

A 22-year-old male is complaining of a refractive error which is stable since 3 years ago. He has been diagnosed to have KC and he is suffering from his glasses because of aberrations.

His MR is (Table 4.8.1) is:

His old correction is (Table 4.8.2):

Slitlamp examination shows clear corneas with no stress lines. Other ocular examination is within normal limits.

For educational purpose, only the right eye will be studied.

Figure 4.8.1 is corneal topography, and Fig. 4.8.2 is the anterior curvature map of the right eye.

4.8.1Step 1: Analyzing Step

1. The patient is young; he is 22 years old, but according to his complaint and to his old refraction, his refractive error seems to be stable.

2.The BSCVA is acceptable.

3.Both corneas are clear with no stress lines.

4.Corneal topography of the right eye:

•Figure 4.8.1 is corneal topography of the right eye. Corneal thickness at the thinnest location is 441 m, the maximal K-reading is 50.2 dpt, and the Km is 46.3 dpt.

•Figure 4.8.2 is the anterior curvature map. The cone is eccentric, and according to the author’s classification, the pattern is 7.

5.According to Krumeich, it can be considered as grade 1–2.

4.8.2Step 2: Management Suggestions

Table 4.8.3 summarizes patient data and the corresponding individual suggestion(s) for treatment, and presents with a final summary of the best management.

Management summary: CXL and PRK? or ICRs

4.8.3Step 3: Discussion Step

Supposing that the case is stable, there are several options for management:

1.Contact lenses: This option should be always kept in mind.

2. CxL and TG PRK: Attention should be paid to the available thickness and to the allowed amount of ablation, here is 40 m, which may be enough to regularize the central 5 mm of the anterior corneal surface especially that its astigmatism is very small.

3.ICR implantation is also an option.

ICR implantation was performed to the right eye.

Four months after the operation, the patient was unsatisfied and the results were unsatisfactory!

His postoperative MR is (Table 4.8.4):

Table 4.8.4 Postoperative manifest refraction

It is clear that both spherical and astigmatic components increased. UCVA remained the same and the patient lost 2 lines of his BSCVA!

To understand the cause behind this clinical problem, the change that happened on corneal topography should be studied carefully. Figure 4.8.3 is postoperative corneal topography. Figure 4.8.4 is postoperative curvature map. Going back to Fig. 4.8.2, it is an eccentric cone and the pattern is 7 (author’s classification), in which the steep axis cannot be identified, the topographical axis is 90º, whereas the clinical axis is 135º! Fig. 4.8.5 is a comparison between the preoperative and postoperative

topography, there is an induced astigmatism (red circles), and the cone was pushed toward the center of the cornea resulting in more irregular astigmatism and iatrogenic spherical component as shown in the postoperative manifest refraction (see Table 4.8.4).

Finally, this case is presented to show that the results in this pattern are unpredictable and the ICR choice was not correct. May be CxL with TG PRK was a better alternative.

Fig. 4.8.5 Topographical changes after ICRs implantation. There is an induced astigmatism (red circles), and the cone was pushed toward the center of the cornea resulting in more irregular astigmatism and iatrogenic spherical component. A (the left

column) is the post-op map; B (the middle column) is the pre-op map; and C (the left column) is the difference map representing the achieved results