Flattened corneas after photorefractive keratectomy (PRK) do not appear to worsen visual outcomes, a new analysis suggests, offering reassurance to surgeons treating high myopia.
Study compares thousands of eyes
Researchers examined records of 17,019 myopic eyes that underwent PRK. The cohort was split by postoperative keratometry values into a control group and a flat‑cornea group.
Initial results raised questions
At first glance, the flat‑cornea eyes showed higher astigmatism and poorer corrected distance visual acuity (CDVA) as well as uncorrected distance visual acuity (UDVA). The authors noted that these differences could stem from baseline characteristics and surgical variables rather than the corneal curvature itself.
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Propensity matching narrows the gap
After propensity score matching, the two groups displayed comparable CDVA and UDVA, and safety profiles were similar.
Flat corneas do not worsen vision.
Context and prior assumptions
Historically, clinicians have assumed that a markedly flattened cornea after PRK might compromise visual quality. Prior reports hinted that extremely flat corneas do not necessarily predict worse outcomes, leaving the issue unsettled.
One earlier investigation mentioned that postoperative flattening alone was not a reliable predictor of visual performance, but the sample sizes were limited. The new, larger dataset adds weight to the argument that corneal flattening is not intrinsively detrimental.
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Clinical implications
For surgeons, the data suggest that aggressive ablation—often required for high myopia—can be performed safely. The risk of inducing excessive flattening appears less concerning than previously thought. This may influence preoperative counseling, especially for patients worried about the long‑term impact of corneal shape changes.
Patients with high myopia often face a trade‑off between achieving the desired refraction and preserving corneal integrity. The analysis’s results could shift that balance toward more confident correction strategies.
Limitations and next steps
The review is retrospective, relying on existing medical records. While propensity matching reduces bias, it cannot eliminate all confounding factors. Prospective studies could verify whether the lack of association holds across different surgical techniques and patient populations.
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Moreover, the follow‑up period was not specified in detail, leaving open the question of whether long‑term stability might differ. Future research might also explore how corneal biomechanics interact with flattening and visual quality.
Takeaway for patients
Patients considering PRK for high myopia can discuss these findings with their surgeon. While flattening of the cornea after the procedure is common, it does not automatically mean poorer vision. Informed consent discussions should incorporate this emerging evidence, alongside other known risks and benefits.
For more background on corneal curvature and its measurement, see the Wikipedia entry on keratometry.