Simple magnification is the type most often used or mentioned in general publications or manufactures of lenses.

The lower the power the condensing lens the farther from the eye it must be held. The stronger the power the condensing lens the closer it must be held toward the eye. The relationship is very simple, for it is based mainly on the focal length of the condensing lens. Ideally one wants the light from the condensing lens to focus perfectly within the pupil of the patient's eye. This placement will result in the condensing lens forming an image of the retina, in front of the condensing lens, which fills the whole lens.

(1) Assuming you have positioned and adjusted the binocular indirect ophthalmoscope (B.I.O.) for your P.D. you align the illumination system to minimize glare and reflections. If you have a B.I.O. that allows independent mirror placement of the illumination system the illumination is usually placed in the upper 1/3 of your field for superior retina examination and lower 1/3 for the inferior retina. If you have a Topcon without a mirror control knob you will have to tilt the whole illumination and eyepiece housing slightly to move the light source up or down.

(2) Before trying to use the condensing lens you must first view the fundus reflex. When you have observed the fundus reflex, then place the condensing lens before the patient's eye. You should see the pupil of the eye and eyeball within the condensing lens, slowly pull the condensing lens toward you until the whole lens fills with the retinal image. Later, you will get the feel for the correct distance and simply flip the lens into place.

(3) To examine a undilated eye but your B.I.O. does not have a small pupil feature, move each of the eyepieces outward just far enough so you still have some degree of stereopsis. Use the median size aperture setting and reduce the illumination. Examine both peripheral fundi then the posterior poles The amount and extent of the peripheral retina that can be evaluate without dilation is limited by the size of the patient's pupil. Examination out to the equator is usually the limit of any Small Pupil B.I.O. instrument. However, there are exceptions when you can examine out to the ora serrata. It is important the patient never looks into the light. The posterior pole and macula areas are examined last. Otherwise, the patient's pupil will constrict making the rest of the examination almost impossible.

(4) Most B.I.O.'s have convex lenses built into the eyepieces ranging from +1.75 to +2.50D's depending on the manufacture. These lenses enable the examiner to relax their accommodation and view the aerial image of the retina.

(5) The retinal image seen by the examiner will appear larger if the examiner moves closer to the patient. However, the condensing lens must be moved to maintain the conjugation of the pupils.

(6) The patient's refractive error really has very little affect on the size of image seen with the B.I.O. (exception being refractive errors greater than plus or minus 5 to 6 diopters).

• (1) Patient's pupil size
• (2) Power of the condensing lens
• (3) Over all size of the condensing lens
• (4) Refractive error (very small amount )
• (5) Distance the condensing lens is held from the patient's eye

TROPICAMIDE (Mydriacyl®) is used to dilate your eyes which comes in only 1% or 0.5% ophthalmic solution. There are generic equivalent drugs e.g., Tropicacyl & Spectrocyl used in the clinic. They are anticholinergics, which block the sphincter muscle of the iris and the ciliary muscle resulting in dilation an a slight cycloplegic effect. Use only 0.5% tropicamide and nothing else on patients who have very narrow angles. It will enable satisfactory dilation without substantial risk for angle closure.

(7) If the angles are very narrow you should reschedule the patient for the dilated fundus examination (DFE). It is always prudent to perform the dilation early in the day, when appropriate emergency care is more readily available. Always dilate the eye with the narrowest angle first, to ascertain the results, before dilating the fellow eye.

(8) When dilating patients who have narrow angles and a angle closure is possible, always recheck their post dilation IOP pressures. Pressures will be highest at mid-dilation, or within about one or two hours of post dilation. The patient should understand they could be in the office for an additional hour and a half to two hours.

Correct Condensing Lens Direction: There are two ways to determine if the condensing lens is being grasped correctly. Most lenses are coded either with a white or silver ring, this side is placed toward the patient's eye. Also, if the light reflection images from the front and back surfaces are of equal size, the lens is being held correctly.

BIO Examination Procedure: I prefer to examine both eyes at the same time allowing quick comparison of both peripheral fundi pigmentation and appearance. In the clinic patients are examined in the examination chair and usually are not reclined. When examining the superior fundi the patient should be elevated above the examiner allowing for a maximum superior view. The nasal, temporal, and the retina directly above and below the posterior poles are examined with the patient at the examiners eye level. When examining the inferior fundi the patient should be lowered with the examiner standing, again giving the examiner a maximum view of the inferior fundi. The posterior pole of the optic nerve and macula are examined last. As beginners you will want to develop a technique that permits a thorough overlapping examination, this will necessitate having the patient look in at least 11 to 12 different directions.

Suggested Smooth Approach to Examining the Peripheral Retina When Both Eyes are Examination at the Same Time.

The shape of the pupil and retroillumination seen with the BIO will change as the patient's direction of gaze changes from primary to secondary areas. Hence, the amount and extent of peripheral retina seen within the condensing lens will also vary. The condensing lens will not be totally filled with retina in far extreme directions of gaze, unless, the pupil is fully and maximally dilated.

It's important to remember if you have the patient looking up you are viewing the superior retina. This is true in all directions of gaze "whatever direction a patient is looking that's the part of the retina you are viewing" and drawings are made with this in mind.

(A) Represents The True Location Of The Peripheral Retina (B) Represents The Whole Peripheral Retina Of (A) As Those Areas Would Appear Within The Condensing Lens.

The reason retinal mapping is being presented is because an extented ophthalmoscopy procedure requires the findings be accurately represented. Plus, it has been on some state board examinations, however, to the best of my knowledge all states have discontinued this practice.

The B.I.O. and condensing lens give an inverted and perverted view of the structures of the retina. All you do when making a drawing is turn the mapping paper up-side down so the (six (6) o'clock position) is toward the patient's forehead. Then draw things just the way they appear within the condensing lens, but at the inverted clock position of the mapping paper. When you have finished, turning the mapping paper back to its normal position, twelve (12) o'clock toward the forehead, this gives you a true anatomical representation of your findings. In the clinic you will not have mapping paper and must think in terms of what part of the retina you are viewing. If it is the superior retina the scar, lattice or whatever, will always be drawn in the superior field at a given clock position. You must think in terms of proper location (e.g., equator) then draw the scar or whatever correctly.

In the event a narrow angle closure starts to occur, what should you do? You've dilated the patient and their intraocular pressure is climbing (increasing) say from 10 or 16mmHg up to 30 mmHg post-dilation, but the IOP has not yet reached 45 mmHg or 55 mmHg you need to take some mode of action. There are several differing opinions on how to handle the situation.
#1. Use 1 or 2% pilocarpine placing 1 drop (i gtt) in the eye every five (5) minutes, maximum of four times or six (drop) applications. Five minutes later instill one drop (i gtt) of a beta blocker like Betagan® (levobunolol) or Timoptic® (timolol) continue to monitor IOP. Some advocated Diamox® (Acetazolamide) be used prier to the pilocarpine; however, there are some serious side affects. Some of those follow:

• 1.) Contraindicate: in patients with impaired renal function
• 2.) Contraindicate: in patients with known sulfa drug hypersensitivity
• 3.) Contraindicate: in patients with liver disease
• 4.) Contraindicate: in patients with severe pulmonary congestion

#2. Instill two drops (ii gtts) of 0.5% Rév-Eyes® (Dapiprazole) followed five minutes later with 2 more drops. Next instill (i gtt) of Betagan® (levobunolol) five minutes later recheck IOP. Repeat gonioscopy, evaluating the presence of angle structures previously visible before dilation. If the angle is continuing to close, mechanically applanate the cornea with the gonio lens to help open the angle thus facilitating outflow. Be careful if the pressure is high the patient is likely to vomit when this procedure is done. Option #1. would be the procedure I would suggest for an induced angle closure where the pressure is still not too high.

Why not use Rév-Eyes® on narrow angle patients? You could if this is your normal standard operating procedure. Rév-Eyes® is not intended nor marketed for reversal of angle closure. This is clearly stated in their product insert information sheet.

You should be monitoring the patient's pressures, every five minutes. Remain calm, twenty minutes at this point can seem like an hour. If the patient's intraocular pressure reaches 45 or >50mmHg the eye's sphincter muscle becomes paralyzed and pilocarpine treatment is not affective. You must get these patients to a ophthalmologist for management and possible laser peripheral iridotomy. The availability of secondary intervention is the very reason you're doing the dilation in the morning.

It should be noted pilocarpine when used on patients under 40 years of age will cause headaches and increase in myopia caused by induced ciliary muscle spasms. Pilocarpine is a direct-acting cholinergic agonist. Because of its activity at the cholinergic receptor sites on the iris sphincter and ciliary muscle, it causes pupillary constriction and varying degrees of ciliary spasm. The precise mechanism by which pilocarpine reduces intraocular pressure is not known. The most widely accepted explanation is its direct stimulation of the longitudinal muscle of the ciliary muscle, which in turn, exerts an effect at the scleral spur thus widening the trabecular spaces and increases aqueous outflow. Dr. Malinovski, in another class, will go into more detail on this very subject.

Points of Interest: The ora is narrowest nasally and widest temporally. The dentate processes are more marked on the nasal side of the retina. The choroid and retina end at the ora and at this point the choroid becomes the pars plana which looks very much like normal retina.

Early metastatic carcinomas are frequently mistaken for serous retinal detachments, therefore, transillumination of the globe may help make the differential diagnosis. Turn the B.I.O. off and transilluminate the eye with a direct ophthalmoscopy or transilluminator. The area of concern is viewed with the B.I.O. still off and with the condensing lens. An unpigmented lesion such as a metastatic carcinoma will be seen as a dark zone against the glow of the fundus, whereas a serous retinal detachment, will not be seen, blending in with the normal fundus background.

(1) Clean the lens using hard contact lens cleaner (Lobo) and warm tepid water, NOT HOT WATER. Then dry by blotting the lens with a soft lint free cloth or paper towel.
(2) Never autoclave or boil a condensing lens.
3) Place the lens completely in 3% hydrogen peroxide solution, Zepherin 1:1000, or Pure 70% Isopropyl Alcohol for 5-10 minutes.