The intriguing problem of progressive myopia is quite complicated, and as of this writing, has not yet been solved. It is generally thought that part of the problem is inherited, and part is acquired, over the years, as a result of over working the visual system [1].

Reviews various aspects of the progressive myopia problem [2]. Develop a first-order control system approach to the development of emmetropia and myopia [3]. Show the effects of variable daily nearwork cycles on the progression of myopia, which compares well with animal experiments (correlation r = 0.97) [4]. Discusses open-loop and closed-loop control system equations to predict the exponential and linear time course of corrected and uncorrected myopia development [5]. Develop an analog computer model of myopia development, which automatically solves complex control system equations in an accelerated time frame [6]. Review the effects of excessive nearwork on myopia development during the college years [7]. Review the effects of various new types of reading glasses, in terms of slowing myopia progression [8]. Present a complete review of myopia research [9].

development, consisting of a resistor, capacitor, battery, and square wave oscillator. Each component represents a particular aspect of the visual system and environment. The resistor represents the slowness of the system to respond, in terms of the RC system time constant, which is the order of 0.3 to 1.0 years. The battery (typically -3 to -8 Volts for -3.00 to -8.00 diopter myopes) represents the optical power of the corrective lenses. The square wave oscillator, varying from 0 to -3 Volts, represents the near-point reading work load of the student throughout the day. For instance, during a typical day, a student (or office worker) might read at a distance of 13 inches (i.e. -3.00 diopters, or -3 Volts), for 1 or 2 hours in the morning, 1 or 2 hours in the afternoon, and 1 or 2 hours at night, resting the visual system (at I (t) = 0 Diopters = 0 Volts) during the intervening 3 intervals, for 1 or 2 hours during each of these 3 segments, with non-study related activities, e.g. television, dining, coffee breaks, exercise, etc.

Figure 1: RC series circuit diagram. I (t) = input (t), o (t) = output (t).

9Figure 2) shows a typical law student, studying at an effective optical distance of -3.00 to -4.00 diopters. Figure 2 shows a 4-element DC series circuit, with an applied AC square wave, used to predict the time course of progressive myopia. Figure 3 shows the positive effects of using reading glasses during near work study, effectively lessening the amplitude of the applied square wave. Figure 4 show that +3 Diopter reading glasses reduce the effects of the negative battery from -5 Volts to -2 Volts. 

Figure 2: Norman rockwell’s the law student, sat. Evening post, febr 19, 1927.

Near work induced transient myopia (NITM) and accommodative lag (AL) are the subjects of extensive clinical and laboratory research in recent years, which can be modeled and predicted using relatively simple analogue electrical circuits, as shown here [10].

The Equivalent Circuit

Freshmen engineering students at college, and indeed nowadays modern High School students, are entirely familiar with standard RC (resistor capacitor) circuits, in terms of their response characteristics to either DC (battery = -Vo) or AC (oscillator = -V(t) ) applied loads. However, the myopia problem is a little more complicated (Fig. 2), involving the simultaneous application of both AC and DC voltages to the circuit. As a practical matter, solving these combined differential equations is quite difficult, but the series circuit (basically an analog computer) automatically solves the equations, predicting the time course for years of progressive myopia, in just a few minutes. The results can be observed with an ordinary voltmeter or oscilloscope (Figure 3,4).

Figure 3: Effect of +2.00 D. Reading glasses on magnitude of square wave.

Figure 4: Equivalent circuit shows the effect of +3.00 D reading glasses (battery reduced from -5 Volts to -2 Volts).

Applications To Pathological Myopia

As shown in Figure 2, the effect of increasing degrees of myopia ( greater than -6 to -7 diopters) is to stretch the sclera, which subsequently damages the lens, vitreous, retina, choroid, and optic nerve (see for instance Troilo 2019).

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