The retinal image quality characterized by the modulation-transfer function of the eye was measured for two groups of subjects aged in the late twenties and mid sixties, respectively. In both groups, we obtained modulation transfer functions by using a double-pass method under the same experimental conditions: 4-mm artificial pupil, paralyzed accommodation, and objective control of the refractive state and centering. Results showed lower values of modulation in the retinal image for older subjects compared with the younger subjects. The modulation transfer function ratio is similar to that previously found for contrast-sensitivity measurements with subjects in the same age groups. These results suggest that a significant fraction of the loss in spatial vision with age has an optical origin. Apart from the well-known increase in intraocular scattering, there also appears to be an increment in ocular aberration that causes an additional reduction in the contrast of retinal images.

An experimental study of the retinal image quality in aged subjects after their eyes have been implanted with intraocular lenses (IOL's) has been performed. The method is based on recording in vivo the aerial image of a point test, after a double pass through the ocular media, and subsequent computation of the eye's modulation transfer function. The optical performance of three different types of bifocal IOL is compared with that of conventional monofocal IOL's. The results show that eyes implanted with bifocals exhibit a mean reduction in the modulation transfer function (contrast in the retinal image) of a factor of 2, while keeping a resolution similar to that of monofocal IOL's (which explains why visual acuities are also similar in these two cases). The mean retinal image modulation in eyes implanted with monofocal IOL's is ∼2.5 times lower than that obtained with young emmetropic subjects, but it seems to be similar to that corresponding to # of persons of the same age (∼60 years) normal eyes.

There is an increasing tendency to treat RD with primary vitrectomy, which is related to neither a higher complexity of cases nor better anatomical results.

Surgical approach modifies risk factors of PVR, and should be taken into account to improve the models for predicting it.

A case of cutis marmorata telangiectatica congenita (CMTC) is described in association with congenital glaucoma. Approximately 68 cases of CMTC and only four cases associated with glaucoma have been reported. The type of glaucoma seems to be related to an abnormality of the filtration in the anterior angle, due to increased pressure in the episcleral vessels. The surgical treatment is trabeculectomy, and opening an alternative drainage pathway.

No abstract

To implant intraocular lenses (IOL) is a common technique in cataract surgery. At the beginning, only monofocal lenses were used, but lately also different types of multifocal IOLs are available1. In the evaluation of postoperatory visual performance, contrast tests, such as CSF, are replacing visual acuity, since contrast is recognized as a key parameter in both optical quality (Modulation Transfer Function, MTF) and visual performance (Contrast Sensitivity Function, CSF). Although the CSF contains information about the optical quality of the eye, it strongly depends also on retinal, neural and even psychological factors. MTF estimates of IOLs are usually available by both designer computations and optical bench measurements. However the real MTF of the implanted eye could largely differ from these previous estimates, because of many factors such as subject variability, lens decentering, shifts, tilts, etc. In consequence a direct measurement of the MTF is necessary, if one really wants to know the resulting optical performance of the implanted eye.

No abstract