CA2009841C - Method and apparatus for ocular perfusion - Google Patents

Abstract

Ocular perfusion during intraocular surgery of the anterior or posterior ocular cavity is optimized through the method of using a gas pump having a discernible and controllable output pressure to pressurize a reservoir of liquid infusate, which is supplied under pressure to a surgical infusion instrument for perfusion of the selected ocular chamber (Gas Forced Liquid Infusion, GFLI). The infusate selection and the infusate pressure can be controlled with a high degree of accuracy and both can be rapidly varied by audible command. Preferentially a human sensible indication of pressure is constantly available at the gas pump.

Description

FE3, i .i Q0 10: ~
P. 1/ 1 ''- 2(~09~34~!.

~F.~ t I P L I ON

MRth~A ~n~ ~nn~-r~t~ nr s~clll ar pAr~1lcion F~ el A ~f ~ ~ Tnvsnt~ ~n The pr~sent invQnt~on relates ~QnQrally to apparatus and method~ used in ~urgsry CQ~'lCtQa on the eys- More particularly, the pr~sen~ in~Qntion rQlates to apparatus u~ed ln continuou6 ~nfusion procss~s as~ociatsd w~th ~uch ~u~ge~y. ~n ~ven greater particularlty, thQ prssent lnv~ntion rQlate~ to appa~atus for accurately and rapidly controlling th~ in~usion pres~ure to th~ eye and rapidly converting between liquid and gas ~ nfu6ion during such ~o surg~ry.

Rs~ ro~lnA of t-~e Tr~v~nt~Q~
Intraoperative control of intraoçular in$u6ion prQ~sur~ i~ an importan~ par~meter in eye aurg~ry. Liguid pre~6ure regulatlon has been acco~pli~hed in mo~t part u~ng gravity-fed systems ~nvolv~ng the relatlve height o~
the infu~ion ~ottle above the eye. A disc~s6ion of the d~velopmQnt of gas lnfusion ~ay ~e found ln "Vitreou6 ~icro6urgeryl~ by Steven Charles, M.D. in Willia~s ~ ilkin~, 1981, volu~e 4. As noted thers$n, t~ere ars known power injeotor~ or pumps which are capa~le of ma~nta~ning an accurate intraocular pre6~ure during air lnfu~ion, as co~pared to manual 6yrlnge injection. 8uch dsvlce~ have al~o b~en devQlopeB wh~reln a mioroco~pressor is u6ed to producs an ~n~low o~ gas ~p~n~nt upon in-traocular pree~ure.
A~ the~e advance~ ar~ ~ade in ga~ inf~sion apparatus,a n~ed exist~ for controlled in~raocular in~sion method and apparatuS which would facilitatQ the ~nte~changeabil-~a ~

ity of gas infusion and llquid infusion during surgery on theposterior segment of the eye (vitrecyomy). Additionally, during surgery on the anterior chamber of the eye (cataract extraction~ the need exists for more accurate, surgeon controlled and monitored liquid infusion.
During cataract surgery, the most common operation performed in the United States, the surgeon views only the anterlor chamber of the eye as shown in FIG. 5, havlng no method of slmultaneously monltorlng the posterlor segment.
Slnce the anterlor chamber ls qulte small, containlng only 0.25cc of llquid volume, small and momentary aspiration flow rates exceeding infuslon rates will result in anterior chamber collapse, as shown in FIG. 5. The consequence of anterior chamber collapse is damage to the non-reproduclble monolayer of cells (endothellum) which llnes the inner surface of the cornea, keeplng it clear of fluld. Thls endothellal damage can then result ln cloudlng of the cornea, with the need ~or subsequent cornea transplanation.
The terms "closed eye" and "closed wound" as used ln this appllcation are synonymous. The terms "closed eye" or "closed wound" in the context of thls appllcatlon refers to closed eye or closed wound intraocular eye surgery. Closed eye or closed wound lntraocular eye surgery is a surglcal method whereln lncomplete temporary closure of the surglcal lnclslon is performed prlor to lrrigatlon/asplratlon cataract context removal. A portlon of the wound is left open, large enough only for the surglcal lnstrumentatlon. Ideally, normal intraocular pressure ls maintalned durlng surgery by adequate wound closure and lnfusion pressure. Thls normal intraocular pressure durlng surgery is referred to as a "closed eye" or "closed wound" system.
It is common for cataract surgeons to perform incomplete temporary closure of the surglcal lncision prlor to lrrigation/asplration cataract cortex removal. A true "closed eye" or "closed wound" system is never achleved, and anterior chamber collapse in this condition ls a slgn of wound leakage of infusion liquids rather than of inadequate lnfusion .~

8 6~ ~
."~......................................................... .
2a pressure. If anterior chamber collapse is encountered, the ~ wound should be checked for tlghtness.
The cataract surgeon's most common defense against perceived anterlor collapse ls lncreaslng of lnfuslon pressure by ralslng a gravlty-feed infusion bottle an estimated height above the eye as shown in FIG. 4. Note that gas is not commonly lnfused into the anterior chamber in such surgery.
In practice, bottle height is not measured, so that actual pressure dellvered to the eye ls unknown, and ls presumed to be sufficient when anterior chamber collapse no longer occurs.

C

FEB! 12 '90 lO:d2 P. 11/21 1 2 2~ 8~
~, , , 3 Un~ortunately, ~o~eal ~ndot~e~ial da~age may al~o occur a~ ~ re~ult o~ h~gh in~u~ate volum~ or ~t~troa~
me~snic~l damag4 ~ro~ ~he u~e o~ hlgh Slow rate~ undor hig~ pressure. ~h~e~ ~freo~ G~G~ re not re4dlly apparent to the su~eon du~ to hi~ inabll~ty t4 peroe~e the ~low rat~ or pr~sure. Retlnal ~tery occl~slon m~y also occur, lnvis~blQ to the surg~on a~d r~eultlng ~n bllndn~ss. Flnally, ~r~s prolap~e through the wound may occur a~ a result or exce~ in~usion ~l~vq~r~.
o JA~-lly~ cataract ~rrigation/a~p~ration ~U~Q
~houl~ be performe~ w~th normal ~cular pro~ure (25mm Hg).
Faillng th~, ln~u~lon ~ r~ ~hould be rals~d a~ llttl~
as pos~blQ to main~aln anter~or cha~er pre~uro ~o avo~d collap~Q durl~g actlve lrr$~at~0n/a6piration. Be~au~e unn~ rlly h~gh lnfu~ion prss~ure an~ ~low ratQ~ can $n~ure retlnal and corne~l t~6slAe~ wlth l~ttl~ w~rnlng to the ~urgeon, ~ncrea~ng ln~lon to th~ ~ye ~ho"~ th~
la6t ~olutlon atte~ptea to remedy anterior cha~ber col-~pe~. A~ pr~lou~ly stated, the Bur~4on ~t~t~ ir~t check a~quate wound clo~ur~. ~urthQr, o~n wlth ~n adequately clo~ed eye, anterlor chamber ~ollapoQ may o¢~ur as a result o~ und~sc~plln~d, con~n~o~Q, h~gh rat~ asp~r-ations. ~gh vacuum a~p~a~on ~ noc0~6rry to achiev~
¢ataract re~oval, but ~ r~ul ~moval of blocks of cataract cort~x matsr~al ~wlth ~u~e~usnt opQnlng o~ ths aopirat~on port) ~hould ke antic~patQd 80 a~ to lntQrm~t-tently reduce thQ a~p~rat~on ~acuu~, avo~dlng anterior chamb~r ~ollap~e. All too ¢ommonly surgeon~ ~ov~ ~bout within t~ ey~ w~th an op~n a~plration port, w$th ~uction con~n~o~ly ongaged.
~ he above di~cu~lon demonotrates the $mportanco o~
a new mQthod of rapld, accurate, ~uxg~on cG..troll~d o~ r lnfuelon ~Gas Fo~ Llquld In~u~on, GF~$).

._ Summary of the Invention The primary object of the invention is to provide the surgeon with a method and apparatus to rapidly and precisely control and monitor his infusion pressure.
It is also an object of the present invention to enable the surgeon to quickly switch between liquid infusion and gas infusion.
Yet another object of the invention is to enable the usage of momentary maximum safe infusion pressure for such purposes as controlling bleeding during surgery.
These and other objects and advantages are accomplished in our invention through a novel arrangement of conduits and valves which allow the constant maintenance of the desired intraocular pressure and the flexibility of using either gas or liquid infusion. The invention utilizes an infusion bottle as a reservoir for the infusion liquid. A continuous infusion gas pump, such as a Grieshaber or Trek Air Pump, is utilized to pressurize the liquid infusion bottle to the desired infusion pressure (Gas Forced Liquid Infusion, GFLI). The output of the pump is also used directly to provide pressurized gas via a conduit for gas infusion to the eye. A conduit from the infusion bottle provides pressurized liquid for infusion. The gas conduit and liquid conduit are preferentially formed as a 20 dual-tube conduit and are connected to a stopcock which allows the physician to select either gas infusion or liquid infusion.
In an alternate embodiment, adapted for anterior chamber surgery, the gas infusion line is eliminated since gas infusion is not commonly used in this type surgery; the flexible conduit connections between the liquid infusate bottle and the eye, and between the gas pressure device and the liquid infusate bottle are maintained. In both embodiments, the output of the gas pump is connected directly to the pressurized gas pocket above the infusion liquid via a conduit extending within the liquid infusion bottle.
In summary, this invention seeks to provide a Gas Forced Liquid Infusion (GFLI) apparatus for controlling intraocular pressure during closed wound intraocular surgery, using a source of continuous pressurized gas controllable to vary gas pressure, a liquid infusate reservoir having a limited volume for maintaining a liquid infusate in the reservoir under pressure with a volume of gas, 10 and an ocular surgical infusion instrument, the apparatus comprising:
(a) a first conduit for conveying pressurized gas from the source of continuous pressurized gas to the liquid infusate reservoir, with the conduit for conveying the pressurized gas extending into the volume of gas contained within the reservoir so that the volume of gas contained within the reservoir is in direct communication with the source of continuous pressurized gas;
(b) a second conduit for conveying liquid infusate from the reservoir to the ocular surgical infusion instrument;
(c) a valving means in communication with the second conduit for controlling the flow of liquid infusate from the liquid infusate reservoir to the ocular 20 surgical infusion instrument;
thereby permitting accurate and rapid control of the infusion pressure during intraocular surgery and avoiding the deleterious consequences of underpressurization or overpressurization and jetstreaming during such surgery.

- 4a -Fck. 12 ~1~ 10.44 P,13/21 '~ Z~9~34~ -.. " 5 Rr ~ DQ~ t ~ On 0~ nr~W~ n-Y~
Appars~us embodying ~eature~ o~ our lnvention are dep~ct~d ~n t~e appen~ed drawln~ wh$ch form a port~on o~
thi~ invention and whe~Q~n:
FIG. ~ ~8 a per~pect~ve ~lew ~owlng the app~ratu~ as used durlng ~urgery FTG. 2 1~ ~ brok~n l~Y-out ~iQw ~owing thQ ~ ntion not in u~e FIG. 3 ie a broken lay-out ~ew show~ng th~ cat~ract 6urgery emb~d~m~nt;
FIG. ~ ~hows the prior art and oc~ structure~; and ~IG. 5 show~ an in~tance o~ oc1~lPr collap~e.

~r~ o~ ~ Pre~ar~A~ J~t FlG. 4 ~llu~tr~t~ th~ co~mon oontrol ~ethodology a~d app~ratu~ for llq~ld $n~usion of t~e 8y~ a~ h~retofor~
u~ed $n c~taract and ln vlL~ s sur~ery. ~IC~ 5 ~8 illw tratl~ o~ co~mon o~lr- collap~e whQn ~slng thQ
method and apparatu~ ~hown ln FIG. 4.
~efQrrlng ~o the ~lguree ~or a ~e~ter undQr~t~n~lng of the ln~entlon, it m~y bQ ~Q~n that thQ ~nventlon l~ ~or u~e with a patient whO 1B lying b~n~ath surglcal drap~
on an operating ta~le ~2. A contlnuou~ lnfu~lon air/ga~
pump 13 i~ lo~ated on an equlpm~nt ~tand ~4 a~ i~ co~vQn-tion~l p~actlce. The outpu~ o~ the alr/ga6 pump 13 i5 25 di~pl~yed a6 by I ED ~ ~ at ~ panel ~6 ~o that the pre~ure generated th~r~y may be ~onltored ~y the ~urg~ry team and prec~Qly co~trolled.
~ h~ output o~ th~ alr/ga~ pump 13 i~ u6ed to pre~-~urize a llquld lnfu~lon b~t~le 23 to pro~$de Ga~ Forced 30 ~$qu$d ~nfu~lon (GF~) of th~ ~ye. Use of G~ Forced Llguld Sn~us~on ~w~th dig~tal nu3Qrlc rea~out of ln~u~$on prQ~ure in vl~w of the -~r~eon) allowe th~ ou~geon ~or th~ rlrst t~e to ~ccur~tely anq contlnuously monltor this ~08t important parameter~ In thls method, ~h~ ~n~u~lon 35 bott~ i8 hung at eye he~ght, ~o tha~ gra~ty ~sed, thQ
pref~rr~d t~chnlque o~ the pr$o~ art, contrlbute~ no ~ .~

FkB, 12 '911 10:45 P, 14/2, ,.......................................................................... .
"-- 2 .... C
. ~, , pr~ur~ to per~u~ion/~nfu~on. R~th~r, t~tal control o~
p~r~uslon pressur~ 1~ instea~ achi~ed by ~n~tilling ln th~ ln~ueat~ battle, ga~ und~r p~e~ur4, pro~lded ~y tne g~ pump. ThR infus~on pre~ure ¢an thQroby be ~etlcu-lou~ly and rapidly ~el~cted by the surgeon.
An antib~ct~rlal ~llter ~n~ctor 17 ~ttac~Q~ a Slex-~bl~ condult to the pump 13 in ~ny con~entlon~l manner a~
i~ well ~nown ln ~he art. Th- ~on~ t ~8 ~xtend~ ~rom t~
equlpm~nt ~tand 14 to n~ar an lV ~u~ol- 19 and term~nat~
lo ln ~ T-conn~ctor 2~ or other ~uitable dev~ce for d~rect~ng th~ alr~low from ~he pump 13 ~long two path~ A flu4d pr~ssur$zatlon conduit 2Z 1~ connQcted betwèen thQ ~-connector al and a com~lne~ ln~us$on bottle w~th drl~
chambe~ 23 ~U~G~ ~ed by the IY ~up~o~ 19 and ~erve~ to preosurize the f~uld th~re~n ~n accor~an¢e with the o~u~
pressure o~ th~ pump 13. Thio ~lU4 d pre~6urlsatlo~ con-~ult extends wlth~n the lnfuo$on bot~le 80 ~ to conne~t the ga~ volume above l~Uld w~th thQ gas pump ~o~ venting ~u~04e8. A ~lu$a deliv~y con~ 4 i8 co~n~cted a~ thQ

2~ output o~ ~nfu6~on bottl~ 23 and term~nate~ a~ one $nput to ~n~u~a~ ~tc~cock ~election val~ 26. An al~ dellvery condu4t 27 1~ connectQd bstw,~-~ th~ remaln~ng branch o~
the T-connector 21 ~nd th~ valve a6. Note t~at valv~ 26 m~y ~e a thrse-way ~nput ~al~ wh~qh would allow oele¢tlon of elthor 11~4id, air, or ~nally an alr/~a~ ~iXture ~Q.g.
sul~ur hexa~luori~ SF~ 20%, p~rfluo~p~opane ~ ~ 1S%) deli~or~d by a ~scond gas pump. ~he ~al~ ~6 ha~ a ~ingle output to an ~u~$on conduit 28 whiah ~ nonn~cted to anB ouppll~ an eyq infu810n cannula 2g.
As shown ln FIG. 1, th~ ~n~usion bottls 23 iB plac~d at thQ p~ient's ~y~ el ~o ~8 to contr~but- no gra~$ty ln~u~1on pres~ure a~ had been cu6tomary in the prlor art.
Air/gaG 15 pum~ed into th~ bottle 2~ oonA~t~ ~8 and 22 to pro~ide the de~red lnfu~on pressur~. Altho~gh a normal ~tartlng pressure may b~ ~el~cted, it ~,ho~ s clear that the ln~u610n pr~ure can be ~apl~ly ~-ng6~ by ~diul3ting the output pre~urQ o~ the air pu~P 13. 5!he ~ir FEE, 12 ?0 10:45 P,15,'21 2 ~

pump 6elected shoul~ hav~ a digital d~play lC o~ the pr~surQ whlch ~hould be ~is$bls to all opQrati~g room per~onn~l. It ha~ bQQn d~te~ined tha~ the d~play~d, condu~t, and intraoc~l~r st~t~c prqs~ure~ agre~ to withln two to fou~ mm o~ ~g uoing ~he pre~nt a~paratw.
~ al~e 26 allow~ th~ surg~cal t~am to qulçkly switch from llquld ~n2u~on to ga~ lnru~lon. ~on~ t~ 24 an~ 27 may b~ formsd ~rom t~e ~wo halve~ o~ ~ tw~n pla~t~c tubQ, ~or ~xample PicoC Tw~n sorQ S~licons IV tublng, such that the ~alvQ 26 may ~e lo~ated ~mm~diate~y proxlma~ to ~h~
~hort c~nn~ 29, th~r~by ~ln~m~zing th~ ti~ and ~olum~
r~guirod to clear $n~u8~0n l~quid ~ro~ the ~y~tQm c~nn~lr ~9 when gas l~ de~lrQd.
From th~ forQgolng~ it ~ay ~e ~n th~t we have lS prov~ded an effecti~Q apparatuo and method ~Ga~ Forced ~iguld Infu~ion, ~F~I) whlch g~Qatly l~p~o~e~ ~he ~ur-g80n1~ ~f~clQncy ln ~ltrectomy operat~on~ ~n which l~uld to g~8 infu~ion chang~ are dQ~irQd and al80 provide~ a readlly controlla~l~ m~an~ for ~arylng the ~n~fiion pro~-sur~ during all liquid ln~u~$on ~y~ ~urgery lnclud~ngcataract -~G~al. ~ well kno~n, lt ~ po6~1ble to stop or reduce ~ n~ by ra~n~ t~Q intr~oc~tl~r pres-6urQ to maximu~ known ~afe leYels, usually 35 to 45 ~m of ~g. Using the pre~ent invent~on w~t~ a dlgi~al dl~play 1~
allows th~ ~urg~cal tQam to guickly de~-ermine the infu~on pre6su~0 lo~ and rapldly chan~e the ~ev~l ~e r~qu~rQ~, to maxlmum ~fe 1QV~1 w~th gr~t ~ccuracy.
It iB t~e a~pect o~ the ln~entlon that allow~ the ourglcal tea~ to contlnuou~ly mon~tor and precl~ly oon-trol th~ in~u~lon pree~ure whlc~ 1~ o~ cr~tical ~mportanceto the cata~act sur~on. ~h~ tubing 6y~tem ahown ~n FIG.

3 u~e~ an an~lbacterial ~lter connector 3~ to ~ttach flsx~bl~ tublng 32 to the ~lr pump 13. ~hQ flsx~bl~ tub-lng 32 $~ co~,n~ted d~ro~tly to t~e inru~ion ~ottl~ 23 whl~h ~ suppl~ed with ~nfu~ion llquld a~ ~hown in F~G. 2.
A ~ngle tlQxible ~-on~ 33 ia provided to carry pre~ur-i~Qd lnfu~lon liqu~d rro~ the bottle to a ~lve 34 which ~ yr~

controls the flow of llquid to the infusion/asplration device 36 used in cataract surgery. With the digital readout 16 available, the surgeon is able to constantly monitor the pressure being utilized in the eye and therefore is at all times aware of and alert to the potential deleterious consequences of overpressurization and ~etstreaming. Thus, due to his ability to monltor and accurately select the intraocular pressure, the surgeon will naturally turn more attention to adequate wound closure and dlscipllned aspiration rather than using a potentially destructive infusion pressure level to prevent ocular collapse.
The use of the gas pump 13 to pressurize the infusion bottle 23 in either of the embodiments above also leads to a significant further refinement in the art. Voice recognition technology can be used to regulate the output pressure of the gas pump 3. Thus, an input microphone 37 is connected to a voice recognition circuit, many of which are commercially available, which in turn outputs a control signal to the pump 13. Preferentially the pump will be provided with a speaker 38 which will enunciate the pressure, subsequent to an instruction to change pressure or upon a query by the surgeon; or upon a variance of the pressure outside a predetermined tolerance. The surgeon's voice may be specifically recognized so that he mlght state the deslred pressure in an audible voice, and the machine would respond immediately that it will seek the commanded pressure after a preset safety delay, in the absence of further commands.
Infusate selector valve 26 may also be voice actuated. For the first time, perfusion pressure to the eye and infusate source can be controlled dlrectly by the surgeon rather than necessitating the presence of other operating room personnel.
Immediate pressure ad~ustment with voice response completes surgeon control of infusion pressure - the most vital parameter characterizing "closed eye" or "closed wound"
surgery.

C

FEB, '2 !~0 10:i'7 P, 17/21 2~0~34~L

Wh~ le we hav~ ~hown our ~ nventlon ln two ~or~, lt wlll be obv$ou~ to tho~o ~killed in ths ~rt that it 1~ not ~o l~lted ~ut ~ su~c~ptlbl~ or ~ar$ou~ ~hang~s and ~odg-f$cation~ wlthout aep~rtln~ ~ro~ th~ ~plrlt thor-o~.

Claims (13)

1. A Gas Forced Liquid Infusion (GFLI) apparatus for controlling intraocular pressure during closed wound intraocular surgery, using a source of continuous pressurized gas controllable to vary gas pressure, a liquid infusate reservoir having a limited volume for maintaining a liquid infusate in the reservoir under pressure with a volume of gas, and an ocular surgical infusion instrument, the apparatus comprising:
(a) a first conduit for conveying pressurized gas from the source of continuous pressurized gas to the liquid infusate reservoir, with the conduit for conveying the pressurized gas extending into the volume of gas contained within the reservoir so that the volume of gas contained within the reservoir is in direct communication with the source of continuous pressurized gas;
(b) a second conduit for conveying liquid infusate from the reservoir to the ocular surgical infusion instrument;
(c) a valving means in communication with the second conduit for controlling the flow of liquid infusate from the liquid infusate reservoir to the ocular surgical infusion instrument;
thereby permitting accurate and rapid control of infusion pressure during intraocular surgery and avoiding the deleterious consequences of underpressurization or over-pressurization and jetstreaming during such surgery.

2. A Gas Forced Liquid Infusion (GFLI) apparatus for controlling intraocular pressure during closed wound intraocular surgery, using a source of continuous pressurized gas controllable to vary gas pressure, a liquid infusate reservoir having a limited volume for maintaining liquid infusate in the reservoir under pressure with a volume of gas, and an ocular surgical infusion instrument, the apparatus comprising:

(a) a first conduit of conveying pressurized gas from the source of continuous pressurized gas to the liquid infusate reservoir such that the pressure within the liquid infusate reservoir is substantially the same as the pressure produced by the source of continuous pressurized gas;
(b) a second conduit for conveying liquid infusate from the reservoir to the ocular surgical infusion instrument; and (c) a valving means in communication with the second conduit for controlling the flow of liquid infusate from the liquid infusate reservoir to the ocular surgical infusion instrument;
thereby permitting accurate and rapid control of infusion pressure during intraocular surgery and avoiding the deleterious consequences of underpressurization or overpressurization and jetstreaming during such surgery.

3. An apparatus for controlling intraocular pressure during closed wound intraocular surgery, using a source of continuous pressurized gas at a controlled variable gas pressure, a liquid infusate reservoir having a limited volume for maintaining liquid infusate in the reservoir under pressure with a volume of gas, and an ocular surgical infusion instrument, comprising:
(a) a first conduit for conveying pressurized gas from the source of continuous pressurized gas to the liquid infusate reservoir such that the pressure within the liquid infusate reservoir is substantially the same as the pressure produced by the source of continuous pressurized gas;
(b) a second conduit for conveying liquid infusate from the reservoir to the ocular surgical infusion instrument;
(c) a valving means in communication with said second conduit for controlling the flow of liquid infusate from the liquid infusate reservoir to the ocular surgical infusion instrument; and (d) a gas pressure control means for variably controlling the pressure of the gas from the source of continuous pressurized gas by audible command signals;
thereby permitting accurate and rapid control directly by the surgeon of infusion pressure during intraocular surgery and avoiding the deleterious consequences of underpressurization or overpressurization and jetstreaming during such surgery.

4. The apparatus as defined in claim 3 further comprising an indication means, in connection with said gas pressure control means, for providing a human audible indication of the pressure of the gas from the source of continuous pressurized gas.

5. The apparatus as defined in claim 3 wherein said gas pressure control means for variably controlling the pressure of the gas from the source of continuous pressurized gas provides an audible signal acknowledging a detected audible command signal.

6. A Gas Forced Liquid Infusion (GFLI) apparatus for controlling intraocular pressure during closed wound intraocular surgery, using a source of continuous pressurized gas controllable to supply a variable gas pressure, a liquid infusate reservoir having a limited volume for maintaining a liquid infusate in the liquid infusate reservoir under pressure with a volume of gas, and an ocular surgical infusion instrument, the apparatus comprising:
(a) a first conduit for conveying pressurized gas from the source of continuous pressurized gas to the liquid infusate reservoir such that the pressure within the liquid infusate reservoir is substantially the same as the pressure produced by the source of continuous pressurized gas;
(b) a second conduit for conveying the liquid infusate from the liquid infusate reservoir to the ocular surgical infusion instrument;
(c) a third conduit for conveying pressurized gas from the source of continuous pressurized gas to the ocular surgical infusion instrument;
(d) an infusate selector valving means for selectively connecting either the second or third conduit to the ocular surgical infusion instrument such that when the second conduit is connected to the ocular surgical infusion instrument, liquid infusate from the liquid infusate reservoir is conveyed to the ocular surgical infusion instrument, and when the third conduit is connected to the surgical infusion instrument, pressurized gas from the source of continuous pressurized gas is conveyed to the infusion instrument; and (e) a gas pressure control means for variably controlling the pressure of the gas from the source of continuous pressurized gas by audible command signals;
thereby permitting accurate and rapid control directly by the surgeon of infusion pressure during intraocular surgery and permitting rapid conversion between liquid and gas infusion during such surgery.

7. The apparatus as defined in claim 6 further comprising an indication means, in connection with said gas pressure control means, for providing a human audible indication of the pressure of the gas from the source of continuous pressurized gas.

8. The apparatus as defined in claim 6 wherein said gas pressure control means for variably controlling the pressure of the gas from the source of continuous pressurized gas provides an audible signal acknowledging detected audible command signals.

9. The apparatus as defined in claim 6 further comprising a valve position audible-control means connected to the infusate selector valving means for selectively controlling the connection of either the second or third conduit to the ocular surgical infusion instrument by audible command signals.

10. The apparatus as defined in claim 9 further comprising a feedback means for acknowledging response of the valve position audible-control means.

11. A Gas Forced Liquid Infusion (GFLI) apparatus for controlling intraocular pressure during closed wound intraocular surgery, using a source of continuous pressurized gas controllable to supply a variable gas pressure, a liquid infusate reservoir having a limited volume for maintaining a liquid infusate in the reservoir under pressure with a volume of gas, and an ocular surgical infusion instrument, the apparatus comprising:
(a) a first conduit for conveying pressurized gas from the source of continuous pressurized gas to the liquid infusate reservoir, with the conduit for conveying the pressurized gas extending into a volume of gas contained within the liquid infusate reservoir so that the volume of gas contained within the liquid infusate reservoir is in direct communication with the source of continuous pressurized gas;
(b) a second conduit for conveying the liquid infusate from the liquid infusate reservoir to the ocular surgical infusion instrument;

(c) a third conduit for conveying pressurized gas from the source of continuous pressurized gas to the ocular surgical infusion instrument;
(d) an infusate selector valving means for selectively connecting either the second or third conduit to the ocular surgical infusion instrument such that when the second conduit is connected to the ocular surgical infusion instrument, liquid infusate from the liquid infusate reservoir is conveyed to the ocular surgical infusion instrument, and when the third conduit is connected to the surgical infusion instrument, pressurized gas from the source of continuous pressurized gas is conveyed to the infusion instrument;
thereby permitting accurate and rapid control of infusion pressure during intraocular surgery and permitting rapid conversion between liquid and gas infusion during such surgery.

12. The apparatus as defined in claim 11 further comprising a valve position audible-control means connected to the infusate selector valving means for selectively controlling the connection of either the second or third conduit to the ocular surgical infusion instrument by audible command signals.

13. The apparatus as defined in claim 12 further comprising a feedback means for acknowledging response of the valve position audible-control means.