PART 2 MICROFLUNCTUATIONS IN ACCOMMODATION2ai) what is the origin of the large spikes in the traces?The large spikes are due to the subject blinking.2aii) the accommodative stimulus was positioned at 4.25 D for the top trace; how accurate was the accommodative response?The accommodative response in the trace was approximately 3.6 D. This is less than the accommodative demand of the 4.25 D. Thus the accommodative response was not accurate. The accommodation error is positive (0.65D), which means the subject has a lag of accommodation.2aiii) an astigmatic lens combination was placed in front of the subject and the stimulus again positioned at 4.25 D. Where was the subject focussed in relation to the circle of least confusion and the two focal lines traduced by the lens?The +1.12/-2.25 DC x 45 lens in crossed cylinder form would be +1.12 DC x 135/ -1.12 DC x 45. The accommodative response in the trace is approximately 3.6 D. The accommodative demand is 4.25D. Thus, the response is less than the demand and the subject has a lag of accommodation with an accommodation error of 0.65D. The astigmatic lens image would lead to a focal line, a circle of least confusion, and another focal line. The first focal line is at -1.12 D from the retina. The second line focus is at 1.12 D from the retina. The object would be focussed at (1.12-0.38 D) =0.74 D, and thus favour the second focal line. 2aiv) From the power spectra, what can you say from the relative amplitudes of the low frequency bands in the two records, about the focusing system of uncorrected astigmats?The low frequency peak of the non-astigmatic subject is lower than that of the astigmatic subject. Also the low frequency graph of the astigmatic appeared to have more variability. Low frequency is representative of image blur, which the astigmatic patient experiences to a greater degree, since the image would not focus to one point compared to an emmetropic patient.2bi) compare both the raw traces and their Fourier spectra; what can you say if anything about the likely origin of at least some of the accommodative microflunctuation evident in the raw data?Some of the accommodative high frequency microflunctuation seen in the raw data is due to instantaneous pulse. Some of the low frequency microfluctuation is due to spikes in instantaneous pulse and respiration.

PART 3 AGE-RELATED CHANGES IN ACCOMMODATIVE AMPLITUDE3i) Analyse the relationship between amplitude of accommodation and age.Amplitude of accommodation appears to decrease with increasing age. This is supported by studies (Kasthurirangan & Glasser, 2006) . The relationships can be described by a linear regression line. The linear relationship is relatively strong. The coefficient of determination is 0.84 for right eye and 0.85 for left eye. There are outliers in the data possibility due to human variability, chance, or experimental error during the testing procedure. For instance, during the push-up method, the point of blurring as stated by the subject may not have been exact due to subjectivity. The measurement of the distances with a ruler may not have been very accurate. Thus, technique may have been compromised in some readings.