a 80-year old female with an axial length (IOLMaster) 26.42mm for OD and 27.66 mm for OS. Keratometry reading was 44.12/45.92D (K1/K2) and 44.35/45.73D (K1/K2) for OD and OS, respectively.
The fundus was like a high myopia.
The refractive error for this patient was -2.5DS (OD) and -3.0DS (OS).
Was this normal?
In my opinon the patient really has a high myopia based on axial length and IOL calculations, confirmed by fundoscopy reading. As I understand the doubtful for you is subjective refraction -2.5 and -3.0, which could be explained by changed refraction of sclerotic and partially clouded lens with shift into hyperopia, that is why distance correction required for this patient is less that real power of Myopia
Thank you for your answer. The ACD values deeper than normal range, is this a possible factor affecting the refraction?
Consider changes in refraction index of the lens and changed in its hydration due to glycaemic fluctuation: is the patient diabetic?
Lenticular changes and diabetes typically cause a shift to greater myopia, not less myopia. I am surprised there is no refractive astigmatism, given the K's noted above. Do you know what the refractive power of the eyes were when the patient was 50 years old? Could be that her lens has less refractive power than would be normally expected to compensate for this axial length and corneal curves to give the lower refractive error noted above.
The ACD values deeper than normal range could not be a possible factor affecting the refraction, since refractive power of aqueous humor in AC is very low comparing to refraction of cornea- 2/3 and the lens 1/3.
Regarding the lens -aforementioned myopic shift could be in case of intial cataract due to increased water content in the lens and the same mechanism in diabetes in high sugar levels and the patient coukld have VA fluctuations during the day due to fluctuations of sugar, but in contrast to mentioned in phacosclerosis stage could be hyperopic shift which I suppose in presented case.
What was the best corrected VA ? I think the final prescription is more than that is prescribed because the IOL power calculated comes between 8-10D with different A-constants as you have shown. Please recheck refraction. The myopia should be at least 8 -10 D, in my opinion.
Hello,
according to what you wrote I suppose that the refractive error (-2.50 & .3.0) is considered in subjective refraction too. It's a very important specification to find an answer to your interesting question.
I give my own opinion from the most probable reason to the less one:
1) there is an higher percentage of hyperopia with cortical cataracts. In your patient are there cortical cataratcs? This could be a plausible reason.
2) Hypoglycemia cause hyperopia. This patient may have had hypoglycaemia at the time of the visit. What's your opinion above?
3) Retinal changement of central macula could cause hyperopia (tipically serous central chorioretinopathy,) even old ones if not completely absorbed.
4) several drugs can induce hyperopia and other refractive errors.
Please give us your opinion. It's an interesting question. Kind regards.
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