BRIEF DESCRIPTION OF THE DRAWINGS
Some of the objects of the invention having been stated, other objects will appear as the description proceeds when taken in connection with the accompanying drawings in which:
FIG. 1
a is a perspective view of a first embodiment of the meibomian gland evaluation tool according to the present invention showing a small tip for evaluation of one or just a few glands.
FIG. 1
b is a perspective view of the first embodiment of the meibomian gland evaluation tool according to the present invention showing a larger tip for evaluation of several glands.
FIG. 2 is a broken away side view of the first embodiment of the meibomian gland evaluation tool according to the present invention.
FIG. 3 is s perspective view of a second embodiment of the meibomian gland evaluation tool according to the present invention.
FIG. 4 is a broken away side view of the second embodiment of the meibomian gland evaluation tool according to the present invention.
FIG. 5 is a broken away side view of a third embodiment of the meibomian gland evaluation tool according to the present invention.
FIG. 6 is an exploded side view of a forth embodiment of the meibomian gland evaluation tool according to the present invention.
FIG. 7 is a broken away side view of a fifth embodiment of the meibomian gland evaluation tool according to the present invention.
FIG. 8 is broken away side view of a sixth embodiment of the meibomian gland evaluation tool according to the present invention.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
While the present invention will be described more fully herein after with reference to the accompanying drawings, in which a particular embodiment is shown, it is to be understood at the outset that persons skilled in the art may modify the invention herein described while still achieving the favorable results of this invention. Accordingly, the description which follows is to be understood as a broad teaching disclosure directed to persons of skill in the appropriate arts and not as liming upon the present invention.
Referring to the figures and particularly FIGS. 1 and 2 in which a first embodiment of the of the invention is shown, the meibomian gland evaluation apparatus generally indicated at 100 comprises an elongate shaft or handle 105 having a bore 110 there through. Located at one end of handle 105 is an annulus 112 the purpose of which will become evident as the description proceeds. One end of handle 105 mounts a cap 115 having a bore there through 117 and the opposite end of handle 105 mounts a second end cap 120. The caps may be threaded, press fitted or otherwise connected, depending upon the particular fabrication technique and materials employed. For purposes of illustration only, cap 115 is press fitted and cap 120 is threaded. It will be noted that in most instances the present invention will be used in conjunction with a slit lamp and that the shaft should be of an appropriate dimension to be used in conjunction therewith.
A probe tip 200 is mounted for longitudinal movement relative to the handle 105 such that when the probe tip 200 is placed against the eyelid and compressive force is applied, movement of the handle 105 a preselected distance replicates the approximate force required for natural expression of secretion from the meibomian gland. Testing has determined that this force is approximately 15 grams per 30 mm2 however; depending upon the age, gender, race or other factors, this force may be between 10 grams per 30 mm2 and 20 grams per 30 mm2 or even up to 40 grams per mm2 in some cases. Probe tip 200 is detachably connected to one end of a shaft 125 which is operatively associated with handle 105. Probe tip 200 is fabricated from a soft biocompatible material such as natural or synthetic rubber, Polyester® or other inert/non-allergenic or biocompatible materials, well known to those skilled in the art. As shown in FIGS. 2 and 4, probe tip 200 is cylindrical and may be dimensioned to as to overlie one or more meibomian glands. An alternate embodiment of probe tip 200 is shown connected to the handle as illustrated in FIG. 3 and in that embodiment is designed to test a larger section (approximately ¼) of the eyelid to simultaneously evaluate multiple meibomian glands for gland function. Probe tip 200 may be press fit, snapped or threaded on to the end of shaft 105. In addition, while the specification refers to a probe tip of 30 mm2, it us to be understood that this size is exemplary of probe tips and that larger or smaller surface areas may be employed with equal efficacy, depending on the preference of the clinician, the equipment employed, the degree of obstruction present as well as other factors which may appear. Thus, the pressure per unit area to be tested will remain-substantially unchanged. For example, a probe tip of 15 mm2 will have a pressure ranging between 5 grams per 15 mm2 and 10 grams per 15 mm2 according to the parameters set out above. Stated otherwise, under normal circumstances the probe tip will apply between ⅓ and ⅔ grams per mm2.
Per FIG. 2, shaft 105 also includes an annulus 130 proximate the tip mounting end. As shown, shaft 125 is inserted within bore 110 for longitudinal movement. A helical spring 130 is operatively associated with shaft 105 and surrounds a section thereof, biasing the shaft out of the housing. Annulus 113 serves as a support or bearing surface for spring 130.
As illustrated in the second embodiment of the invention, shown in FIG. 3, the apparatus may also include an indicator means or indicator generally indicated at 300 for indicating when handle 105 has moved the preselected distance. The indicator means 300 may be selected from the group consisting of auditory, visual and tactile signals. Any of the just mentioned signal means may be employed so long as activation thereof does not significantly impact the force required to move the handle to ensure that the pressure delivered to the eyelid remains in the required range. The indicator means 300 comprises a visual indicator means or light emitting diode (LED) 305 mounted in end cap 120 such that the light emitting portion is at least partially external of the cap and the electrical leads 310 (schematically shown) extend down into the bore 110 and are connected to a battery contact plate 315 also within handle 105. A battery 320 is provided proximate the battery contact plate 315. The LED is activated by movement of the handle 105 which causes the end of shaft 125 to complete the electrical circuit and illuminate the LED. Movement of the handle 105 away from the eyelid opens the electrical circuit and turns off the LED. Circuits of this nature are well known the art and a detailed discussion thereof is not deemed necessary. Buzzers, vibrators or other indicator means may also be employed as visual indicator means.
In the embodiment of FIG. 5, the meibomian gland evaluation tool 100 is generally similar to the previously described embodiment except that the shaft 125 is substantially stationary and the means for sensing when the preselected pressure has been reached comprises a piezo-electric or other similar strain gauge device 400 in combination with an amplification circuit 410 (shown schematically) and which is well known to those skilled in the art. When the preselected pressure has been exerted on the eyelid, the amplifier is activated and the indicator means 300 is triggered. It is believed that this embodiment will be produced using molding techniques wherein the cylindrical handle 105 will be produced in two longitudinal halves and will be press fit together.
In the embodiment of FIG. 6, the preselected pressure is supplied by a spring means or constant force spring 500 which has a spring constant selected to deliver the preselected pressure to the eyelid. The constant force spring is coiled and has a connection opening 505 at the outer end. In this embodiment, it is again believed that the handle 105 will be molded in two opposing longitudinal sections that will be press fit together. One half of handle 105 is provided with upper stop 160 and lower stop 165 in the form of protuberances extending into the bore 110 which operate to limit the travel of probe shaft 125, as will be described more fully herein below. In addition, one side of the handle includes a tang 140 extending from the inner handle wall towards the center of the bore 110. The tang 140 should be of a diameter to receive the opening in the center of constant force spring 500 and should be of a length sufficient to maintain the spring in place when the two halves of the handle are connected together. The other end of spring 500 is connected to a tang 150 located on shaft 125. In the “at rest” state of this embodiment, the spring 500 is in the coiled position and tang 150 is in contact with upper stop 160. Pressure exerted on the probe tip by movement of the handle 105 causes the spring to uncoil until tang 150 contacts lower stop 165. An indicator means is not provided as the constant force is delivered merely by unwinding spring 500. Further, it is believed that the clinician will sense when the shaft has reached its maximum path of travel when tang 150 contacts lower stop 165, but the indicator means which could buzz, flash, vibrate, or illuminate when shaft 125 is in the operating range between stops 160 and 165 previously described, could also be included with this embodiment of the invention.
FIG. 7 illustrates an alternate embodiment of the invention wherein the handle shape is rectangular and box-like. Shaft 125 includes a mounting bracket 127 to which one end of an over center spring or compression spring 600 is connected. As a compression spring is normally expanded, the first end rests in a cavity or pocket 141 in handle 105. The opposite end of spring 600 is connected to the handle by means of a pin or tang formed in the handle housing and the shaft is biased in the extended or outward position. Pressure on the eyelid acts to compress the spring 600. When shaft 105 is pushed past the center position 127 or 141, shaft 105 will retract away from the eyelid. The device may be reset by pressing a reset button (not shown), but well known to those skilled in the art.
FIG. 8 illustrates another embodiment of the meibomian gland evaluation tool 100 wherein the shaft 125 is connected to handle 105 with a cantilever beam 700. A piezo-electric transducer or strain gauge 400 together with actuator circuitry identical to that discussed in connection with the embodiment of FIG. 5. Pressure on probe tip 200 causes strain gauge to output a signal proportional to the applied pressure. When the preselected pressure has been reached, the actuator circuit activates LED 305.
In operation the clinician selects the handle 100 having the desired probe tip 200 or mounts the desired probe tip 200 at the end of shaft 125. The probe tip 200 is then placed on the external surface of that section of the eyelid to be tested for meibomian gland function. The clinician also equips themselves with the proper equipment (appropriate magnification from a hand held lens, head magnifier, slit lamp, microscope etc.) to be able to observe the meibomian gland orifice(s) in order to monitor whether secretion is expressed from the orifices of the meibomian gland with the application and the continuation of the compressive force. A compressive force in the form of gentle pressure is exerted upon the eyelid by pressing the handle 105 towards the eyelid which compresses spring 130. Just prior to the end of shaft 125 makes contact with the battery contact plate 315, the force of 15 grams per 30 mm2 is reached in a user independent manner and the clinician observes whether the meibomian gland is properly secreting or not, and the type of abnormality of secretion varying from total obstruction to compromised secretion. The apparatus is designed so that just prior to activation of the indicator means, the cumulative force or energy stored in the spring is substantially equivalent to the force required for natural meibomian gland secretion. Of course, the other indicator means are actuated in the aforementioned manner as well.
In another embodiment (not shown) of the meibomian gland evaluation tool 100, the shaft 125 may be connected to handle 105 which is attached to a coil spring of constant force which rotates and provides force either directly on the eyelid or by pushing a linear rod attached to the handle 10S which applies force on the eyelid.
It will be noted that this apparatus of the present invention may be fabricated as a disposable, single use item primarily from plastic materials, or alternatively, may be fabricated as a multiple use probe with disposable tips, in which case that portion of the device that is re-used will be fabricated from materials of sufficient durability to withstand repeated autoclaving and/or alcohol sterilization, as appropriate for the materials chosen.
The foregoing embodiments and examples are to be considered illustrative rather than restrictive of the invention, and those modifications which come within the meaning and range of equivalence of the claims are to include therein.
Patent Application
20080082057
