why my child feel blur this week?

why my child feel blur this week?

I always met boys or girls under 14 years old who complained that I could not see clearly recent weeks. Parents took them to optometry doctor to get new pair of glasses. After you put on positive lens on them, and a while, you will find no more glasses were need. The boys or girl were always watching TV or computer for a long time or reading for a highly long tense. At this circumstances, you have to prescribe mydriatic to them instead of prescribing new eye glasses. A review should be performed two weeks later.

Can you swim after lasik?

Swimming after lasik?

Swimming after lasik is allowed, but if you are in six months after surgery, no swimming is recommended. Because the water containing the disinfectant in the pool would destroy the recovery strength between the corneal layers.

How much does lasik eye surgery cost?

How much does lasik eye surgery cost?

You first go to hospital for a thorough exam for your eyes. If you are wearing your soft contact lens, put off them for at least 2 weeks; if you are wearing your rigid gas permeable contact lens, just put off them for at least one month before you go to your doctor.

After routine examinations such as visual acuity, subjective and objective, intraocular pressure, corneal topography, diameter of the pupil, corneal thickness, length of axis and sometimes wavefront aberrations of your eye, doctor will analyse the data and tell you if you are suitable for refractive surgery. After analyzing the data, the surgery plan will be made as a function of your corneal thickness. Lasik is the most popular surgery plan in current. But now there are evidences to show surface-ablation-like is in regression. The surgery cost of lasik is about $1000. PRK is a little less. But the medications after PRK are more and long.

What would cause blindness from bleeding behind the eye?

Trauma is the first reason of the blindness from bleeding behind the eye. Such as orbital compound fractures and orbital emphysema(often seen in medial orbital wall fractures) that are caused by fighting, skiting, falling and traffic accidents related to the head and faces.

The second reason is hypertension or high level blood-fat and cholesterin that would occlude the vessels behind the eye. Occlusion would finally lead to bleeding.

Tumor, general blood system diseases like leucocythemia are the uncommon etiological factor.

Principles of four wavefront aberrometers

The Tscherning aberroscope projects a grid of points onto the retina, the distortion of the grid of points is photographed, and the wavefront aberrations are calculated from this distortion.

The Hartmann-Shack wavefront sensor technique relies on the projection of a point source light on the retina. The light reflected from this point on the retina is imaged onto a lenslet array and sampled with a charged coupled device chip. Wavefront aberrations are calculated assuming that a point of light on the retina was the origin of the image.

The Skiaskopy technique effectively performs retinoscopy at multiple points over the pupil, and from these data, multiple refractive errors of the wavefront over the entire exit pupil were calculated.

The laser ray-tracing technique, which we used in this study, projects a thin infrared laser beam onto the retina and detects the location of reflection one by one in succession. This is sequentially completed over 64 sampling points within 0.06 seconds, so that the eye movement does not affect the measurement. The merit of this technique is that it can detect larger magnitude errors of reflection than Hartmann-Shack methods and that it is more rapid and sensitive than the Tscherning methods that essentially require averaging of data from each sampling point.

Principles of high-resolution Shack-Hartmann Sensor Aberrometry

A low-power, invisible, plane laser-wave is directed into the eye.

It is focused on the retina by the refractive power of the cornea and the lens.

The retina absorbs part of this light, the other part is reflected and goes back through the optical media of the eye.

The optical aberrations along the light path within the eye lead to distortions of the wavefront exiting the eye.

The distorted wavefront hits the Shack-Hartmann Sensor consisting of an array of 1,500 micro-lenses and a low-light CCD sensor in the focal plane of the lenses.

The deviations of all spots from their regular positions (in reference to an incident wave) are measured and from these values the optical aberrations are computed in the form of Zernike polynomials.

Advantages:

High resolution

High accuracy and reproducibility

Fast measuring & analysis

Wide dynamic range

High resolution data need powerful software and hardware tools for evaluation of aberrations

Disadvantages:

Wavefront may not be suitable for all patients. In order to determine if you are a good candidate for the wavefront treatment, come in for a pre-operative evaluation at our Clinic.

Principles of Tscherning Aberrometry:

A collimated laser beam illuminates a mask with a regular matrix of 168 pinholes to form a bundle of thin parallel rays

These rays form a spot pattern on the retina that is more or less distorted according to the optical errors of the eye

This retinal spot pattern is imaged onto the sensor of a low light CCD camera by indirect ophthalmoscopy

The deviations of all spots from the form of Zernike polynomials

Advantages:

Fast measuring

Disadvantages:

Time-consuming set-up

Time-consuming analysis

Low resolution

Diffraction of the laser radiation at the small pin holes disturbs the result

Complicated mechanical and optical arrangement

Patient disturbed by visible flash (green, 532 nm)